A cold atoms gravimeter il a device which measure the gravity with Raman transitions on free falling atoms. Since 2006, the SYRTE research team is working on such a gravimeter, and during my thesis, I will continue their work. Today, this gravimeter is working with an accuracy of 5.7 10^-8. The limits on this result are known: the wavefront aberration. The combination of the velocity distribution of the atoms and the irregularity of the optics create a complicated to evaluate bias on g which fluctuate in time. This cause a degradation of the accuracy and the long term stability. In this talk, I will present the work I did during…

Structured light has recently attracted the interest of scientific society while it is possible to control it in all its degrees of freedom and dimensions. I will present light spiraling like a tornado over its propagation. Such structured light can be generated by superimposing abruptly auto- focusing ring-Airy beams that carry orbital angular momentum of opposite handedness. This results to a complex wave with intense lobes that twist and shrink in an accelerating fashion along propagation. [1] A. Brimis, K. G. Makris, and D. G. Papazoglou, “Tornado waves,” Opt. Lett.45, 280–283 (2020). [2] Dimitris Mansour, Apostolos Brimis, Konstantinos G. Makris and Dimitris G. Papazoglou, "Generating Spiraling Light: Optical Tornados "…

Grid-based binary holography (GBH) is an attractive method for patterning with light or matter waves. It is an approximate technique in which different holographic masks can be used to produce similar patterns. Mask-based pat- tern generation is a critical and costly step in microchip production. The next- generation extreme ultraviolet- (EUV) lithography instruments with a wave- length of 13.5 nm are currently under development. In principle, this should allow patterning down to a resolution of a few nanometers in a single expo- sure. However, lithography with metastable atoms has been suggested as a cost-effective, less-complex alternative to EUV lithography. The great advan- tage of atom lithography is that the kinetic…

We are working on a model partly borrowed from the standard Davydov-Fröhlich models originally introduced to account for electron-phonon interaction in macromolecules. Under the action of an external electromagnetic field on a DNA protein, the energy transferred to the electron shows an electronic current which can display either a spreading frequency spectrum or a sharply narrow frequency spectrum. This phenomenology displays a potentially rich variety of electrodynamic interactions of DNA molecules by the electron excitation. This could imply the activation of interactions between DNA and external electromagnetic fields.

A simple, student lab-level experiment containing interference of two totally independent lasers inside. We used different configurations of lasers, both HeNe and diode ones, to directly obtain interference fringes photos with 27÷87% contrast on typical cameras.

Applications of lasers in quantum metrology require precise control of the laser frequency. This is usually achieved by locking the frequency of a slave laser at a tunable offset from a master laser. Here we present a new scheme for a robust and high precision laser offset frequency locking. A hybrid frequency discriminator generates an error signal that has a wide capture range of more than 180 MHz while preserving sharp resonance needed for a tight lock. The Allan deviation was measured to be less than 12 Hz at 1 seconds and remained below 1 kHz for more than 1000 seconds.

Resonant transmission is a well-known effect in quantum mechanics, often studied in undergraduate physics courses. There is a resonant behaviour in the transmission probability for a square barrier potential. However, this effect is not seen in a gaussian barrier. The lack of resonances is investigated for barriers that start with a square shape and are deformed into a smoother one, with the transmission probability being calculated numerically. Doing so gives insight into the behaviour of the resonances and how the barrier shape can affect their presence.

Using an optical cavity to perform atom interferometry offers several advan- tages; the high-quality wavefronts allows for very long coherence time (20 s) of a spatially seperated superposition held in an optical lattice, and the resonant power enhancement allows the use of simpler laser systems with a fiber opti- cal modulator to generate laser frequency pairs that are needed for performing Raman beamsplitters. However, these frequency components form multiple standing waves in the cavity, resulting in a periodic spatial variation of the properties of the atom-light interaction along the cavity axis. Here, we will describe this spatial dependence and calculate two-photon Rabi frequencies and ac Stark shifts, and confront the…

Bragg-based atom interferometry is the standard technique for atom interferometry using Bose-Einstein condensates as an atomic source. However, as it is unable to distinguish between the two output ports of the interferometer at the final beam splitter pulse, a minimum separation time between the two clouds is required. This reduces the interferometer time compared to Raman methods for a given device size. We present a measurement technique to reduce this separation time by monitoring the phase between a spatial reference and overlapped spatial fringes arising from an asymmetrical Mach-Zehnder interferometer.

This project will give an approach to using multiple frequencies of light to enhance the loading of a Magneto-Optical Trap (MOT). An electro-optical modulator will be used to produce frequency and intensity tunable sidebands, enabling the nature of slowing to be controlled, and thus optimized, by the user. There are some basic computational simulations that have been done so far. The motivation for this project and some basic ideas will be introduced in this presentation.

The idea that time may emerge from quantum entanglement originated from a mechanism proposed in 1983 by Don Page and William Wootters to solve the, so called, “problem of time” that arises in the context of canonical quantization of gravity. The Page and Wootter (PaW) theory consists in dividing the total Hilbert space into two sub-systems and assigning one of it to time. The “flow of time” then consists simply in the entanglement between the quantum degree of freedom of time and the rest of the system, a correlation present in a global, time-independent state. In this framework we do not consider time as an abstract, external coordinate, but as…

In the focusing nonlinear Schrodinger equation, multisoliton ”breathers” may be created from a single mother soliton by quenching the strength of the nonlinear interaction. In ultracold-gas realizations, atop the mother soliton there are quantum fluctuations coming from its underlying quantum many-body nature, computable from the Bogoliubov theory. Post-quench, these fluctu- ations become the fluctuations in the macroscopic parameters of the daughters, which exist in a coherent macroscopic quantum state. We present a mean-field formalism that uses Lagrange brack- ets to compute, from given pre-quench fluctuations, the fluctuations of the macroscopic parameters of the daughter solitons, with results for both the 2-soliton and 3-soliton breathers.

We report preliminary results on the generation of two correlated Forward Four-Wave Mixing (FFWM) signals using cold rubidium atoms. To induce the FFWM process, we use two almost copropagating beams, with linear and orthogonal polarization. We calculate the time-delay intensity correlation function between all four fields to detect correlation and anticorrelation. In addition, the spectral lineshape of the FFWM signals presents an interesting feature. If one scans the frequency of both input beams simultaneously, the spectra will present a dip around the resonance due to the coherent population trapping. We use a simple three-level lambda system and solve the Bloch equations to model this feature.

We analyze a notable class of states relevant to an immiscible bosonic binary mixture loaded in a rotating boxlike circular trap, i.e., states where vortices in one species host the atoms of the other species, which thus play the role of massive cores. The resulting effective Lagrangian resembles that of charged particles in a static electromagnetic field, where the canonical momentum includes an electromagnetic term. The simplest example is a single-vortex system. While a massless vortex can only precess uniformly, the presence of a sufficiently large filled vortex core renders such precession unstable. A small core mass can also enhance the orbit radius or lead to small radial oscillations, which…

Research aim is to develop a compact electronics module for a cold atom interferometer based system using Rubidium atoms (780nm). Laser systems are one of the most critical part of the cold atom system as they have to be stable in terms of optical power, frequency, line width and spectral properties and should also be a compact system. It is also required to control modulator drivers, RF drivers and detection systems by suitably pulsing the devices as per the requirement of the measurement system. In laboratory-based set ups, these devices are accommodated in multiple electronics racks and transportation of the systems will be a bit difficult. Hence, it is proposed…

Continuous superradiant lasers have been proposed as next generation optical atomic clocks for precision measurement, metrology, quantum sensing and the exploration of new physics [1]. Superradiance is a collective phenomenon resulting in an enhanced single atom emission rate [2]. A way to provide the required phase synchronization is coupling a cold cloud of atoms to a cavity mode. This technique has been used to demonstrate pulsed superradiance [3-5], however, steady-state operation remains an open challenge. Here we describe our machine aimed at validating an alternative proposal [6], a rugged superradiant laser operating on the 1S0-3P1 transition of 88Sr using a hot collimated atomic beam. The elegance of this approach is…

Bragg and Raman are the two most important techniques to form beam splitters in atom interferometry. While often used for the same purpose, the two techniques have different physical characteristics that can be exploited in different ways. This allows two methods to be combined to create interesting novel interferometry topologies, such as quantum clock interferometry. In this presentation I will talk about some of the possibilities that utilize a combination of Bragg and Raman transitions, and the new laser system built for Quantus-1 that is able to implement both processes.

Entanglement is central to the modern understanding of quantum systems and the primary resource for upcoming quantum technologies. However, a potential bottleneck for future advances is the need for scalable protocols to detect and characterize entanglement. In particular, there is an increasing demand for procedures that can certify the presence of entanglement in quantum many-body systems. The quantum Fisher information(QFI) is a witness for multipartite entanglement of great relevance to quantum metrology. Unfortunately, it is hard to estimate the QFI so its use as a tool for entanglement certification is limited, for now. In this talk, we discuss recent works that address this issue and demonstrate that the QFI can…

The MIGA project aims at using atom interferometry as a tool to study geophysical signals and demonstrate the applicability of quantum sensors to build a large scale instrument able to conduct high sensitivity gravity strain measurements. Currently under construction at the LSBB (low noise underground laboratory) in Rustrel in southern France, MIGA will comprise 3 atom sources connected by a common laser link for a total length of 150 m buried 300 m underground. I will present the instrument and its status of construction and a preliminary setup that enables us to study and fine tune the head responsible for producing the atoms samples at the core of the experiment.

The universality of free fall or Einstein's equivalence principle (EEP) remains valid despite attempts to find deviations away from it. It is expected through certain theories, that quantum mechanics and general relativity can be reconciled, breaking EEP. The VLBAI presents a state-of-the-art experiment to push the current limits using matter-wave interferometry. Dropping atoms through a 10-m Mach-Zehnder type interferometer, the VLBAI attempts to measure the gravitational time dilation of the delocalized quantum superpositions induced throughout the flight time. This will further push investigations of the EEP into the quantum regime.

Atom interferometers based on Bose-Einstein condensates are expected to be exquisite systems for quantum sensing applications like Earth observation, relativistic geodesy, and tests of fundamental physical concepts. Since the sensitivity of most atomic sensors scales quadratically with the interrogation time, it is beneficial to extend the free fall time by working in a microgravity environment. We report here on a series of experiments performed with NASA's Cold Atom Lab aboard the International Space Station demonstrating first atom interferometers in orbit. By employing Mach-Zehnder-type geometries we have realized atomic magnetogradiometers and successfully compared their outcome to complementary non-interferometric measurements. Current experimental limitations as well as future perspectives will be discussed. These…

Quantum waveguides are one of the key components in the development of quantum technologies as they are crucial in the transmission of information. The progressive miniaturization of quantum chips requires the waveguides to follow certain paths and so they need to be bent in order to be accommodate onto the chip. Often, waveguides are formed by two straight ends connected by a curved section. While the circular shape is the simplest choice, it generates wave reflection and in turn data loss. It is hence vital to find a protocol that helps designing the geometry of the curved section to ensure high transmission rates. In this work [2] we implemented a…

Mach-Zehnder interferometry using squeezed-vacuum light is an archetype of quantum-enhanced single-phase sensing. Here we propose and study a direct generalization for the estimation of an arbitrary number of phase shifts in d ≥ 1 distributed Mach-Zehnder interferometers (MZIs). In this case, the squeezed-vacuum is split between the d modes of a linear (splitting) network, each output of the network being one sensing mode of a MZI, the other input being a coherent state. We predict i) the linear combination of phase shifts that can be estimated with optimal sensitivity, given a specific splitting network; and ii) the splitting network that allows the estimation of a specific linear combination of phase…

Cold atom interferometers (AIs) have proven to be extremely sensitive and accurate inertial sensors measuring gravity [1], gravity gradients [2] and rotations [3]. Unlike classical sensors, they do not require any calibration and exhibit an inherent long-term stability and accuracy : they are promising candidates for geodesy, geophysics or inertial navigation. We present our progress towards the development of a cold-atom inertial measurement unit, a device measuring each component of acceleration and rotation. We demonstrate two techniques allowing to perform acceleration measurements using a Mach-Zehnder type AI in a single diffraction regime, even for atoms with close to zero velocity. The first technique lifts the degeneracy between the two Raman…

Atom Interferometers as inertial sensors were getting quite some interest in the last decade. The superior sensitivity of the sensors is mostly reached by large interrogation times of the atoms. For high-rate navigation scenarios, however, the long measurement intervals and preparation times of the atoms lead to severe systematic errors in the navigation solution. In this contribution a quite promising combination of the atom interferometer and a classical inertial measurement unit (IMU) in an error state extended Kalman Filter framework is presented. This approach aims especially on improving the performance of the conventional IMU, while the drawbacks of the quantum sensor are negated.

Entanglement has been generated in different atomic systems to improve the sensitivity of phase estimation measurements [1, 2]. However, it is challenging to make use of this entanglement in inertially sensitive atom interferometers. One approach is to generate the entanglement directly in momentum space using nonlinear interactions in Bose-Einstein condensates [3, 4]. In our approach, we first create highly entangled states in spin states and then transfer this entanglement to momentum states. This technique generates entanglement in wellseparated momentum modes and is therefore an appropriate candidate for future entanglement-enhanced quantum sensors [5]. [1] L. Pezz`e, A. Smerzi, M. K. Oberthaler, R. Schmied, and P. Treutlein, Quantum metrology with nonclassical states…

The measurement of the gravitational acceleration through light-pulse atom interferometers is a current topic for matter-wave based inertial sensing. Such interferometers have been developted in analogy to optical Mach-Zehnder interferometers, where beam splitters and mirrors are realized by diffracting light pulses. In this contribution, we will present two types of tunneling-based gravimeters: The first one resembles an optical Fabry-Pérot interferometer. The matter-wave cavity is described by two Gaussian barriers, so that reflection and transmission are determined by the tunneling effect instead of diffraction. In the first configuration, we study the effect of gravity on the transmission through the cavity. For the second gravimeter, we prepare the effective ground state of…

Atom interferometry with neutral atoms has proven to be highly sensitive to inertial effects and this has made it a very significant area of research. Gravimeters based on atomic interference not only offer the ability to measure the value of local acceleration g with high accuracy, but also help validate highly relevant principles such as Einstein’s Equivalence Principle. The implementation of a gravimeter requires a series of well-defined elements such as the vacuum system, including the interferometric region, the laser system for the cooling, control and detection of atoms, and the control system to control the experiment. This work shows the progress of the construction of the first dual quantum…

Current calculations and experiments on quantum electrodynamics (QED) both achieve twelve digits of accuracy [1] making it an excellent test ground of the fundamental physics and searches for new physics. Two fundamental constants are obtained from hydrogen spectroscopy with highest precision: the Rydberg constant and the (rms) proton charge radius. While coherent sources in the deep UV are of great interest for both fundamental and applied physics, their usage has been so far limited by the difficulties to generate narrow line width laser sources in this region. Two-photon direct frequency comb spectroscopy [4] offers several unique features in this respect: efficient harmonics generation, low noise and narrow line widths, convenient…

Time-space crystalline structures merge the ideas of time and space crystals to form a system that is periodic both temporally and spatially. The spatial part of the crystalline structure is created by an optical lattice and the temporal periodicity is engineered by choosing a proper resonant periodic driving of the spatial part. In the one-dimensional case, each site of the driven lattice comes equipped with a periodic temporal structure arising from the periodically oscillating localized wavepackets. Such a procedure creates a two-dimensional time-space crystalline structure. Extending the system to three spatial dimensions realizes a six-dimensional time-space crystalline structure which allows to probe high-dimensional condensed matter physics.

Rutherford scattering is usually described by treating the projectile either classically or as quantum mechanical plane waves. We treat them as localised wave packets and study their head-on collisions with the stationary target nuclei. A comprehensive study of the quantum solutions reveals that the paradigmatic Rutherford scattering experiment is asymmetric in time. This nonclassical feature is traced back to the convexity properties of Coulomb interaction. Finally, we sketch how these theoretical findings could be tested in experiments looking for the onset of nuclear reactions.

The aim of the project is to stabilize the Toptica DLC pro laser (780nm) by locking at F=2→F’=2, 3 crossover of 87Rb via Zeeman driving. A saturation absorption spectroscopy setup is designed to obtain the hyperfine levels of Rubidium with Doppler background subtraction. A resonant LC circuit of frequency 511 kHz is used for the Zeeman modulation of the atomic levels. The error signal obtained using a lock in amplifier setup is used for locking the laser at the required frequency. This will thereafter be used for cold atom experiments.

In this work we present a low-order relativistic correction to the multipolar atom-light Hamiltonian for two bound particles corresponding to a simple model for hydrogen-like atoms and ions. From this result, we can systematically predict frequency shifts in atomic clocks based on trapped ions due to the mass defect. We derive the fractional frequency shift with by the use of T-periodic ladder operators, treating the full dynamics of a Paul trap including micro-motion and non-perfect traps, finding accordance with previous results and new corrections with the cross talk of gravity and the so called excess micro-motion.

Trapped and guided Sagnac interferometer have an advantage of achieving large effective area compared to free space Sagnac interferometer, which can increase the sensitivity of the rotation sensor. We are in the process of building such a rotation sensor. Our scheme employs atom chip that produce quadrupole fields in ring geometry and radio frequency chip to dress the atoms in the ring. Taking advantage of opposite signatures of Lande g-factors of clock states of 87Rb atoms, our scheme offers state dependent guidance of two clock states which can rotate in ring quadrupole to realize rotation sensor.

Firstly, I will introduce a thermodynamic cycle using a Bose–Einstein condensate (BEC) with nonlinear interactions as the working medium. Exploiting Feshbach resonances to change the self-interaction strength of the BEC allows one to produce work by expanding and compressing the condensate. Then I investigate the effect of the shortcut to adiabaticity on the efficiency and power output of the engine and show that the tunable nonlinearity strength, modulated by Feshbach resonances, serves as a useful tool to enhance the system’s performance. Furthermore, I would like to explore the thermodynamical characteristics on the coupled density spin BEC driven by the quintic self-attraction in the same- and cross-spin channels. In addition, a…

The sensitivity of atom interferometers to detect small changes in gravity is very important. Among other factors, the sensitivity of these devices is limited by the interference fringe contrast. Contrast is itself limited by dephasing, the decoherence of the Rabi oscillations of atoms over time. One method of reducing contrast which hasn't been explored much in the literature is by using a more optimum intensity profile of the interferometry beams incident on the atoms. Hence, I will present a method of determining the optimum profile of an atom interferometer for dephasing reduction. This is based around finding the appropriate trade-off between beam profile uniformity (which reduces dephasing caused by the…

In this work, I report the realization of a novel optical lattice for the manipulation of ultra-cold atoms, where arbitrarily large separation between the sites can be achieved without renouncing to the stability of retroreflected lattices. Superimposing two short-wavelength optical lattices with commensurated wavelengths, about 1µm each, I realize an intensity periodic pattern with a beat-note like profile where the regions with high amplitude modulation provide the potential minima for the atoms, which experience an effective lattice period around 10 µm. I employ a Bose-Einstein condensate to measure the energy gaps between the first three bands and study in-trap Bloch oscillation with negligible interaction in presence of small external forces.…

In the past decades considerable efforts have been made in orderto understand the critical features of long-range interacting models, i.e. those where the couplings decay algebraically as r^(−d−σ) withσ >0. According to the well-established Sak’s criterion for O(N) models, the short-range critical behavior survives up to a given σ∗≤2. However, the applicability of this picture to describe the the two dimensional classical XY model is complicated by the the presence, in the short-range regime, of a line of RG fixed points,which gives rise to the celebrated Berezinskii - Kosterlitz - Thouless (BKT) phenomenology. Our recent field-theoretical analysis finds there is not a specific, temperature-independent, value of σ∗: while for σ…

I present a scheme that would allow for the controlled motion of cold atoms around a Sagnac interferometer through use of Radio-Frequency (RF) dressed magnetic traps. Multiple interesting geometries of traps have already been created for atoms in the microkelvin range. This talk will aim to give a brief overview of RF dressed traps, give examples of traps that have currently been realised in our experiment, and finally explain how these dressed traps may be used to perform atomic interferometry.

Dispersion forces, such as van der Waals forces between neutral particles or Casimir-Polder forces between neutral particles and dielectric surfaces, are caused by the ground-state fluctuations of the electromagnetic field. They can be understood via an exchange of virtual photons that are generated as a dipole response of the particle due to the vacuum fluctuation of the field surrounding it. These resulting forces are weak for large separations and dramatically increase with decreasing distances. To this end, in matter-wave scattering experiments, where the beam particles reach close distances to the diffracted object, which is typical in the order of a few nanometers, these forces dominate the interaction and have a…

Light pulse atom interferometers are implemented for precision measurements in various areas such as gravito-inertial measurements or measuring fundamental constants. In addi- tion, atom interferometers with an increased sensitivity are potential candidates for testing fundamental physics in gravitation, dark sector physics, or for gravitational waves detection. In order to increase their sensitivity, a promising idea is to increase the momentum sepa- ration between the two arms of the interferometer. We are at present constructing such a Large Momentum Transfer (LMT) atom interferometer. Bragg diffraction is a corner stone for new schemes in the LMT beam splitters. In this “poster” session, I will present a 80 h ̄k LMT-interferometer based on sequential high order…

Supersolids are a fundamental state of matter in which the same atoms that form a crystalline lattice are also responsible for the coherent flow of mass, typical of superfluids. In 2018, my group realized for the first time a supersolid phase in a quantum gas of strongly dipolar atoms. During the talk, I will focus on our latest work, in which we measure the moment of inertia of the dipolar supersolid [1]. We find that the moment of inertia of the supersolid is lower than the classical value, although the crystalline structure increases the moment of inertia compared to that of a standard superfluid. Our measurement directly demonstrates the superfluid…

Recently self-emergence phenomena, like glassiness and crystallization, have been extensively studied using pumped condensed atomic samples, coupled to a high finesse optical resonator. So far most of these experiments have been realized in standing wave cavities, which impose the resonator geometry to the lattice being formed by the atoms and the light scattered into the cavity modes. Adopting degenerate multimode cavities opens new horizons to study order emergence effects, where compliant lattices between atoms and light can show a dynamical evolution [1]. The optical cavity we use to study self-ordering has a bow-tie geometry [2] and the intra- cavity field is in a traveling wave configuration. Therefore, there are no…

Super- and subradiance have been an active topic of research since the seminal paper of Dicke on collective emission of atoms confined within a distance that is small compared to the wavelength of the resonantly emitted radiation. The behaviour of the single and multiple-excitation states of interacting atoms can be understood in terms of the collective eigenstates of an effective non-Hermitian Hamiltonian, which exhibit enhanced (superradiant) and suppressed (subradiant) decay rates, together with level shifts (collective Lamb shift). Also, recent experiments have demonstrated both subradiance and superradiance in large, dilute atomic clouds. We will present the way such an atomic cloud decays to the ground state with two methods, the…

Atom interferometers with their extremely high sensitivity to inertial forces are an excellent method for investigating and understanding gravity and its gradi- ents. Due to the lack of a unified theory which puts the quantum mechanical nature of the world along with gravitational interactions (best explained by gen- eral relativity), studying gravity using quantum mechanical test sources, such as ultra-cold atoms, is an exciting choice for probing physics at this intersec- tion. In this brief talk, I will discuss work towards the realization of novel atom interferometers based upon Sr and Cd atoms, which posses a common electronic structure with two valence electrons, which provides access to narrow linewidth intercombination…

The marked visibility of graphene is due to the phase shift in the interference colour. The study is based on the analysis of graphene visibility on various substrates and hetero-structures such as transition metal dichalcogenides (TMDCs) like Molybdenum Disulphide (MoS2) and hexagonal Boron Nitrite (h-BN). The visibility of graphene depends on the type of substrate, the thickness of the graphite layer, the thickness of various layers of the substrate and the incident wavelength. A comparison of the theoretically obtained contrast colour plots for each of the particular instances with the experimental images was made. The contrast of the graphite layer on the substrate was then calculated to figure out at which…

In this work, in the context of coupled-mode theory, I studied the discrete diffraction and the self-focusing effect in nonlinear optical lattices, under single-cite excitation. In the one and two-dimensional discrete diffraction, the spreading of the beam occurs due to the coupling between adjacent waveguides, while for a critical power and above the effect of self-focusing occurs. I studied the output distribution intensity for periodic, diatomic, and random lattices in one and two dimensions. It is observed that the amplitude, in which the self-focusing occurs, for periodic and diatomic lattices, has the same value. For random lattices with weak disorder, the amplitude is again the same, while for strong disorder,…

We model an atomic Bose-Einstein condensate (BEC) near an instability, looking for universal features. Instabilities are often associated with bifurcations where the classical field theory provided here by the Gross-Pitaevskii equation predicts that two or more solutions appear or disappear. Simple examples of such a situation can be realized in a BEC in a double well potential or in a BEC rotating in a ring trap. We analyze this problem using both Bogoliubov theory and exact diagonalization. The former describes elementary excitations which display complex frequencies near the bifurcation. We make connections to the description of bifurcations using catastrophe theory but modified to include field quantization.

Vienna’s Long-Baseline Universal Matter-wave Interferometer (LUMI) has successfully demonstrated interference of massive molecules consisting of up to 2000 atoms and with masses up to 28.000 amu. LUMI’s high force sensitivity of 10-26 N has also been used to sense electronic, optical, magnetic and structural properties of a very diverse class of particles. I will discuss new experiments with atoms, complex molecules and future prospects for high- mass metal clusters with improved precision over previous devices.

We demonstrate a compact approach to generate ultracold strontium atoms and report trapping of 4.5 million atoms with a total system size of 0.5m$^3$. A novel ablation technique is implemented where pure strontium solid granules are ablated to produce atomic vapor, which is then loaded and trapped in a 3D magneto-optical trap (MOT) within a low-pressure environment. Using a single-pulse ablation power of 35W, we observe a loading time of 40ms with an average lifetime of 4.5s. The results show great potential for applications in quantum technology and outdoor inertial sensing and precision measurement experiments. The ablation technique also opens possibilities of unprecedented laser cooling for elements such as Tungsten.

Cavity-QED based approaches have succeeded in generating large amounts of entanglement enhancements beyond the standard quantum limit (SQL), which sets a fundamental imprecision on all quantum sensors with unentangled atoms [1,2]. It is now of great interest to apply these cavity-QED approaches to enhance a broad range of quantum sensors including atomic clocks [3] and matterwave interferometers. Here, we demonstrate a rubidium matterwave interferometer with atoms guided by a blue-detuned hollow optical dipole trap as they free-fall along the axis of a high-finesse cavity with cooperativity C≈1. We also demonstrate cavity-enhanced quantum non-demolition (QND) readout of the matterwave interferometer with added readout noise as much as 10 dB below the…

We develop a setup suitable for cavity enhanced levitated atom interferometer which is capable of interaction times of several seconds [1] and for investigating interactions between atoms and electrons (the Quantum Klystron, [2]). Atom interferometry enables high precision experiments allowing for search for new physics [3, 4]. The Quantum Klystron mimics electromagnetic radiation by the non-radiating near-field of a density modulated electron beam to coherently manipulate atoms in the |F = 1⟩ and |F = 2⟩ hyperfine groundstates. The experiment consists of a transfer chamber separated by a valve to a science chamber, which facilitates the exchange of the electron beam source. This also offers the possibility to insert samples,…

A quantum gravimeter measures the absolute acceleration of gravity g using atomic interferometry. In the interferometric process, a cold cloud of 87Rb atoms interact with two counter-propagating laser beams, which are produced from a single beam that is reflected off a mirror located at the end of the gravimeter's flight tube. Thus, to achieve good precision on g among other things, it is necessary to know the phase difference induced by the mirror´s displacements. Here we report advances on the development of a postprocessing vibrational compensation module, carried out in the construction of a portable quantum gravimeter made in Mexico.

Neutral lithium has a relatively simple three-electronic structure and thus accurate theoretical calculations including quantum electrodynamics (QED), isotope shift, and relativistic corrections can be obtained from many-body wave functions. The development of high precision spectroscopy of lithium offers a benchmark to such theories and can be used to determine the nuclear radius and measure the fine structure constant, thus testing fundamental physical laws with higher accuracy. We report the precision measurement of the absolute frequencies, hyperfine splitting, and 2P fine structure splitting in cold atoms of 6Li. Using the stabilized optical frequency comb and developed heterodyne detection technique, the photon shot-noise limited optical spectroscopy is achieved. The measurement of absolute…

The excitation of semiconductor quantum dots often involves an attached wetting layer with delocalized single-particle energy eigenstates. These wetting-layer states are usually appro- ximated by (orthogonalized) plane waves. We will discuss why this approach even in the simpliest case of one (lens-shaped) quantum dot on the wetting layer is insufficient. Quantum states associated to the wetting layer were not expected to show an irregular spatial structure. Differences are also observed with respect to the corresponding energy levels of the system which can be statistically characterized with concepts from the field of quantum chaos. Keywords: semiconductor quantum dots, quantum chaos Publication Link: Morphology of wetting-layer states in a simple quantum-dot wetting-layer…

The iXAtom laboratory aims at improving classical inertial sensors with quantum technologies. In particular, my PhD focuses on developing a 3-axis hybrid inertial navigation system. The atom interferometer allows to measure the inertial components with high accuracy and no bias, while classical sensors have a high dynamic range and provide continuous measurements. If the 3-axis hybrid accelerometer was qualified in static operation, their mobile utilization raises new challenges due to the susceptibility of atomic accelerometers to rotations and vibrations which disturb or even extinguish the measurement signal. Real-time methods are currently implemented to compensate rotations and vibrations, then measurement campaigns will be conducted out of the lab in order to…

Magnetic chip traps are a standard tool for trapping atoms [1, 2]. These are robust devices with multiple fields of use ranging from fundamental physics experiments [3] to applications of inertial sensing [2]. While magnetic traps do provide good confinement potentials, they are not necessarily harmonic, in particular, they can exhibit strong cubic anharmonicity. In this contribution, the methods of designing printable 2D wire guides which compensate for unfavorable multipole moments are discussed. A theoretical approach is proposed to reduce the unwanted multipole moments of a Z-chip trap by introducing a small disturbance to the standard wire configuration. Using a suitable representation of the disturbance, the resulting magnetic field is…

Inertial measurements are the backbone for any highly accurate trajectory determination by tracking and integrating accelerations and rotation rates in all three spatial directions. In principle, inertial navigation provides autonomy and is therefore particularly attractive in areas without a line of sight to satellites (e.g. in buildings, tunnels, or in space) as required by GNSS-based navigation solutions. Established inertial measurement units rely on classical sensors suffering from device-dependent drifts. For long-term stable solutions, they require a correction, usually provided by GPS (GNSS). This type of hybrid navigation fails wherever GPS is not reliably available, e.g. in buildings, underground, in tunnels but also in space applications. Atomic inertial sensors are versatile…

We are working towards a matter-wave interferometer based on Sagnac effect that requires atoms to traverse an enclosed path to accumulate phase. Our scheme relies on time-averaged adiabatic RF-dressed potentials (TAAP) to guide neutral atoms around a circular path which will provide a scalable approach towards building a compact atom-based rotation sensor. I will present to you our method to create a fully guided ring lattice trap on an atom chip setup.

Since the first confirmed detection of gravitational wave (GW150914) on 14 September 2015 by LIGO, the detection of gravitational waves by terrestrial LASER interferometric detectors became a routine job. Despite their high sensitivity (100 Hz region), it is important to consider that such terrestrial interferometric detectors lose their sensitivity in the lower frequency region of gravitational waves owing to various types of seismic vibration noises. In order to overcome this problem atom interferometric detectors with unprecedented sensitivity in the deci-hertz (0.1-10 Hz) region of gravitational wave are being considered and proposed by various matter- wave research groups across the world. Some of the various long baseline state-of-the-art atom interferometric detectors…

Grid-based binary holography (GBH) is an attractive method for patterning with light or matter waves. It is an approximate technique in which different holographic masks can be used to produce similar patterns. Mask-based pat- tern generation is a critical and costly step in microchip production. The next- generation extreme ultraviolet- (EUV) lithography instruments with a wave- length of 13.5 nm are currently under development. In principle, this should allow patterning down to a resolution of a few nanometers in a single expo- sure. However, lithography with metastable atoms has been suggested as a cost-effective, less-complex alternative to EUV lithography. The great advan- tage of atom lithography is that the kinetic…

Imaging is a vital aspect of research in biology and physics. Many interesting samples are very difficult to image because of their minimal interaction with light. I am developing Cavity Enhanced Microscopy (CEMIC) as a novel imaging technique for ultra-low optical density samples. After establishing the technique using artificially created structures, I will explore applications both in Biology and Physics, which will include the inner structure of single cells and the quantum-non-destructive imaging of atoms in a Bose-Einstein Condensate.

Atom interferometers can perform absolute measurements of inertial effects with extremely high sensitivities and long term stability in comparison to its classical counterparts. Their measurement accuracy and long term stability have made them an ideal candidate in areas such as inertial sensing and navigation . While performing measurements in dynamic field environments an atom interferometer’s sensitivity decreases due to inertial noise coupling. Furthermore it can only perform cyclic measurements therefore limiting its high frequency measurement capability. Hybridizing the atom interferometer with a classical inertial sensor by means of correlation will enhance sensitivity and dynamic range over its reciprocal re- sponse. With hybridization we have a quantum and classical sensor measuring…

Hybrid quantum system is used to observe the quantum effects like quantum fluctuations. It consists of an optomechanical system where a micromechanical membrane is strongly coupled to a high finesse cavity using position to polarization converter and couple it into Rb atoms.

we are studying the crack formation due to volcanic eruption and measurements of gravity anomaly due to magma-filled dikes. This is done with the help of quantum gravimeter which is based on atom interferometer. We will also demonstrate the gelatin based model to study the crack propagation . Some other fluids of different densities and viscosity are injected and crack formation is demonstrated in analytical laboratory experiments.

MAGIS-100 is a next-generation atom interferometer under construction at Fermilab that aims to explore fundamental physics over a 100-metre baseline, using the latest atomic clock technologies [1]. The experiment will search for ultra-light dark matter [2] and new forces, while also providing an opportunity to test quantum mechanics at new length scales. The 100-metre baseline will also serve as a technology pathfinder to future gravitational wave detectors in a previously unexplored frequency band. The collaboration will extend the work done with state-of-the-art atom interferometers [3] by applying the same techniques to a system of up to three 10-metre interferometers, organised into two 50-metre drop chambers and connected across a vertical…

Matter-wave Atomic Gradiometer Interferometric Sensor (MAGIS) will be the largest vertical atom interferometry experiment, under construction at Fermilab. It consists of three 10 m atom interferometers across a 100-meter baseline. MAGIS will search for ultralight dark matter, test quantum mechanics in new regimes and serve as a technology demonstrator. The MAGIS-100 experiment is an intermediate step towards a future kilometre-scale experiment, potentially sensitive to gravitational waves in the previously unexplored mid-frequency band. A phase shear imaging is going to be employed in MAGIS-100. This novel imaging technique relies on the precise control of the retro-reflection mirror to imprint spatial fringes across the cloud of atoms by tilting the mirror at…

Quantum gases at near absolute zero temperature exhibit pronounced quantum mechanical effects which make them powerful testbeds for probing complex dynamics connected to open questions in other areas of modern physics, such as quantum optics, quantum information, or condensed matter physics. In this work, we demonstrate one of the applications of quantum gases to the study of condensed matter physics. Two cornerstones of mod- ern condensed matter physics are periodic band structures and spin-orbit coupling. Spin-orbit coupling does not directly lead to a periodic lattice structure in the plane-wave regime and breaks the Galilean invariance. In this work, we demonstrate that the confluence of a spin-orbit coupled BEC and an…

We numerically study the quantum dynamics a bosonic Josephson junction (a Bose-Einstein condensate in a double-well potential) in the context of random periodic driving of the tunnel coupling. In particular, we examine how caustics which dominate the wavefunction in Fock space of the undriven system are affected by kicks which are random in both time and strength. In the limit of weak tunnelling and low number imbalance, the system maps onto the kicked rotor (a paradigm for chaotic dynamics) and can display Anderson localization in momentum space.

The supersolid is a counterintuitive state of matter where atoms, arranged in a periodic crystal-like structure, can still flow coherently as they do in a superfluid. The supersolid has been recently observed in trapped quantum gases of strongly dipolar atoms, emerging from the crystallization of a superfluid Bose-Einstein condensate. In this work, we study for the first time the nature of the quantum phase transition associated with the formation of the supersolid both experimentally and theoretically. Although our supersolids are formed by a single row of density clusters arranged in a periodic structure, we observe two different types of transitions that are reminiscent of the first- and second-order phase transitions…

Supersolid is a state of matter in which coexist both a periodic modulation, characteristic of the solid state, and the ability of the superfluid to flow without any friction. Its theoretical prediction dates back to 1960s, but it was experimentally observed for the first time two years ago, in a dipolar quantum gas. My research work is based on the idea of searching for coherent tunneling phenomena such as Josephson oscillations in this dipolar supersolid, in order to prove the superfluidity of the system. This phenomenon usually needs an external potential barrier through which the tunneling arises, but the intrinsic modulation of the supersolid creates minima in the potential, which…

Raman dressing of Bose-Einstein condensates is a highly flexible technique that pro- vides access to the study of interesting quantum phases. In a narrow range of parameters, an exotic supersolid-like stripe phase exists that combines superfluid properties with the breaking of translational symmetry. By using a weak optical lattice in combination with spin-orbit coupling, the parameter range for which such a state is the ground state of the system can be extended, which has led to the experimental realization of the state in our lab. Here, we study this stripe phase by performing detuning quenches of the Raman dress- ing. We observe sinusoidal oscillations of the spin polarization after a…

One-dimensional ultracold Bose gases with attractive atom-atom interactions support bright matter-wave solitons. Once a fundamental soliton is created, a four-fold quench in the interaction strength produces two daughter solitons. These, due to quantum fluctuations atop the mother soliton, are born in a coherent macroscopic superposition, their relative position described by a nearly minimum-uncertainty wavefunction. We show how this state can be used to effect precision measurement. Despite not being an interferometric scheme, a preliminary analysis shows that it features quantum advantage: a precision that scales proportionally to N, the number of particles in the solitons.

We are constructing an atom interferometer with a large momentum separation between the interferometer’s arms. This would significantly improve atom gyroscopes and accelerom- eters sensitivities. Beyond inertial effects, in our group, we are interested in measurements where the macroscopic spatial separation between the two arms is essential. For example, measurements where the influence of fields between the two arms is studied such as geo- metrical phase shift used for atom neutrality tests or atomic polarizabilities measurements. During the poster session, I will describe our experimental setup: the all optical BEC source and the optical lattice used for Bragg beam splitters. I will present an experimental and numerical characterization of beam…

In optics, caustics are bright, sharp lines and shapes created by the natural focusing of light. Some examples include rainbows, the wavy lines on the bottom of swimming pools, and the patterns produced by gravitational lensing. The intensity at a caustic diverges in the classical ray theory, but can be smoothed by taking into account the wave nature of light. In this work we consider a new type of caustic that occurs in quantum systems due to phase singularities; because phase is such a central concept in wave theory, this heralds the breakdown of the wave description and is an example of a quantum caustic. In particular, we consider analogue…

I will present a systematic approach to calculate the phase shifts associated to a variety of different interferometer geometries in a curved PPN spacetime. This spacetime geometry is a generalization of Einsteins GR and therefore may give rise to novel quantum tests of relativity. The whole analysis is done in a fashion, which is easy adaptable to different experimental setups. The role of time and different coordinate charts is discussed in more detail, since potential errors can arise quite quickly, when certain relativistic principles are not thought of and calculations are done in „the usual manner“ - with potentially measurable deviances.

Precision laser frequency control is a key requirement for experiments in AMO Physics. At infrared wavelengths, single-sideband modulators offer a frequency tuning of several GHz. Such electro-optic modulators have a dual-parallel Mach-Zehnder interferometer structure. By tuning the phases of the interferometer arms, the carrier and the one sideband can be suppressed. However, drifts in the control voltages require their stabilization to enhance suppression. Existing stabilization methods rely on the modulation of these bias voltages which result in residual amplitude modulation of the single-sideband. Here, we present a novel stabilization method that is based on dual-frequency modulation. The discriminants for sideband and carrier are generated by an additional low- frequency modulation…

For fundamental physics to go forward, good use of modern technologies and tools needs to be made. Machine learning and quantum technologies are two examples of tools that can be used to drive physics forward. With ever-expanding datasets coming from space missions, it is becoming increasingly more difficult for scientists to manually analyse data. I am currently working on a project involving the use of machine learning to analyze 16-years’ worth of data taken by the Electron Spectrometer aboard the Mars Express mission to better understand the magnetic field configuration of the Martian environment. Similarly, atom interferometers can be used to answer questions regarding one of the universe’s biggest mysteries,…

Cold atom interferometry has proven to be a promising technology for creating high precision inertial sensors, measuring fundamental constants and testing physics such as the WEP. Currently, cold atom devices are constrained by their size, requiring an entire lab to function which limits portability. A route to overcome this issue is with fully integrated atom chips; where the optics, electronics and vacuum are all incorporated into a single device. Using CMOS technology, we are developing chips with integrated electronics for performing evaporative cooling, rf-dressing, fluorescence detection and magnetic field measurements.

The QUPLAS (QUantum interferometry with Postitrons and LASers) experiment aims to test the gravity theory by measuring the Positronium (Ps) fall in the Earth's gravitational field. Such measurement would be a test of the Weak Equivalence Principle and the CPT symmetry and is further motivated by the lack of information on antimatter that could improve the standard model. The setup and techniques of the experiment, which are in continuous development, involve the three phases of production, preparation, and interference of the positronium beam. To operate with an electrically controllable and focusable atom, the first phase aims to produce negative Ps- ions by impinging positrons on a Na-W target. Ps is…

Building local probes of gravity is of interest for both fundamental and environmental research. A compact as well as precise device for this purpose from the perspective of mobility is the demand and matter-wave interferometry is one of the interesting possible answers. The central idea of our setup is to make a gravimeter incorporating levitated cold Caesium atoms below an atomchip and an optical double well potential for interferometry. Cs is heavy and hence the associated wavelength is shorter indicating a sensitive equipment. A Cs BEC as matter-wave source is also an interesting candidate because of its tunable interactions, which provide an opportunity to explore and optimize it for interferometry.…

Controlling experimental quantum systems is one of the challenges in the last years, both from a fundamental and practical perspective. One of the most significant application is the control of interacting systems, for instance, qubits in a quantum computer. In the latter case, in particular, one wants to perform quantum operations without errors, namely with high fi- delity. However, imperfections in the control parameters, imposed by the technological limits, can generate errors during a quantum operation, degrading the performance of the system. In this contribution, I am going to show that it is possible to properly tune the interaction between the qubits to mitigate static errors generated by, for instance,…

I will present an experimental setup designed for studying electromagnetically induced transparency (EIT) in a ladder scheme of Rb atoms. The highest level of the ladder can be an easily accesible 5D level, as well as the chosen Rydberg state with n about 50. The discrimination of population and coherence effects was performed, showing an important share of double-resonance optical pumping in what is conventionally referred to as the EIT feature.