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.