Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1911.10824

Direct imaging of the order parameter of an atomic superfluid using matterwave optics

Puneet A. Murthy, Selim Jochim

Published Nov 25, 2019• 2 citations
arXivHTMLPDF

Abstract

We propose a method to directly measure the complex phase distribution, superfluid density and velocity field in an ultracold atomic superfluid. The method consists of mapping the momentum distribution of the gas to real space using matterwave focusing, and manipulating the amplitude and phase by means of tailor made optical potentials. This makes it possible to find analogues of well-known techniques in optical microscopy such as Zernike phase contrast imaging, dark field imaging and schlieren imaging. Applying these ideas directly at the level of the macroscopic wavefunction of the superfluid will allow visualization of interesting effects such as phase fluctuations and topological defects, and enable measurements of transport properties such as vorticity.

DOI
10.48550/arxiv.1911.10824

Related papers

Matter-wave Fourier optics with a strongly interacting two-dimensional Fermi gas

Puneet A. Murthy, Dhruv Kedar, Thomas Lompe +5 more

We demonstrate and characterize an experimental technique to directly image the momentum distribution of a strongly interacting two-dimensional quantum gas with high momentum resolution. We apply the principles of Fourier optics to investigate three main operations on the expanding gas: focusing, collimation, and magnification. We focus the gas in the radial plane using a harmonic confining potential and thus gain access to the momentum distribution. We pulse a different harmonic potential to stop the rapid axial expansion, which allows us to image the momentum distribution with high resolution. Additionally, we propose a method to magnify the mapped momentum distribution to access interesting momentum scales. All these techniques can be applied to a wide range of experiments, and in particular to study many-body phases of quantum gases.

arXiv:1408.4680•Physical Review A•Oct 10, 2014•70 citations

Direct imaging of topological edge states in cold-atom systems

Nathan Goldman, Jean Dalibard, Alexandre Dauphin +4 more

Detecting topological order in cold-atom experiments is an ongoing challenge, the resolution of which offers novel perspectives on topological matter. In material systems, unambiguous signatures of topological order exist for topological insulators and quantum Hall devices. In quantum Hall systems, the quantized conductivity and the associated robust propagating edge modes--guaranteed by the existence of nontrivial topological invariants--have been observed through transport and spectroscopy measurements. Here, we show that optical-lattice-based experiments can be tailored to directly visualize the propagation of topological edge modes. Our method is rooted in the unique capability for initially shaping the atomic gas and imaging its time evolution after suddenly removing the shaping potentials. Our scheme, applicable to an assortment of atomic topological phases, provides a method for imaging the dynamics of topological edge modes, directly revealing their angular velocity and spin structure.

arXiv:1212.5093•Proceedings of the National Academy of Sciences•Apr 8, 2013•184 citations

Direct imaging of topological edges states with cold atoms

Nathan Goldman, Jean Dalibard, Alexandre Dauphin +4 more

Detecting topological order in cold-atom experiments is an ongoing challenge, the resolution of which offers novel perspectives on topological matter. In material systems, unambiguous signatures of topological order exist for topological insulators and quantum Hall devices. In quantum Hall systems, the quantized conductivity and the associated robust propagating edge modes - guaranteed by the existence of non-trivial topological invariants - have been observed through transport and spectroscopy measurements. Here, we show that optical-lattice-based experiments can be tailored to directly visualize the propagation of topological edge modes. Our method is rooted in the unique capability for initially shaping the atomic gas, and imaging its time-evolution after suddenly removing the shaping potentials. Our scheme, applicable to an assortment of atomic topological phases, provides a method for imaging the dynamics of topological edge modes, directly revealing their angular velocity and spin structure.

•Dec 20, 2012•2 citations

A phase microscope for quantum gases

Justus C. Brüggenjürgen, Mathis S. Fischer, Christof Weitenberg

Coherence properties are central to quantum systems and are at the heart of phenomena such as superconductivity. In this work, we studied coherence properties of an ultracold Bose gas in a two-dimensional optical lattice across the thermal phase transition. To infer the phase coherence and phase fluctuation profiles, we used direct matter-wave imaging of higher Talbot revivals and introduced a phase microscope based on a site-resolved mapping of phase fluctuations to density fluctuations during matter-wave imaging. We observed the algebraic decay of the phase correlations in the superfluid phase and a linear temperature increase of the exponent. These techniques may enable studying coherence properties in strongly correlated quantum systems with full spatial resolution.

arXiv:2410.10611•Science•Jul 9, 2026•2 citations

Quantum gas magnification of ultracold atoms in optical lattices

Luca Asteria

Abstract Ultracold atoms in optical lattices are a very promising quantum simulation platform, as they provide a very clean system (almost defect free) and allow control over many parameters such as tunneling coupling or interaction strength. Because the typical lattice spacing lies in the sub-micron range, it is technically demanding to resolve exactly the position of the atoms in the lattice using high-resolution optics such as quantum gas microscopy. Here we review the matter-wave protocol of quantum gas magnification that we developed for magnifying the atomic density distribution in the lattice (Asteria et al 2021 Nature 599 571). The atomic cloud, thus magnified by a factor of up to ∼ 90 , can then be imaged in a single-shot even with sub-lattice resolution with standard absorption imaging techniques. Furthermore, the protocol was demonstrated for 3D systems with high filling factors, which are typically impossible to measure with high-resolution imaging. In this tutorial, we will review how this technique can be used for high-resolution imaging of the density distribution and present the results obtained using it as a method to access new observables. We conclude with an outlook focusing on how this technique could be beneficial for a wide variety of physical systems which can be realized using cold atoms. This tutorial expands on the topic of my presentation for the SAMOP 2023 PhD Prize finalist symposium.

Journal of Physics B Atomic Molecular and Optical Physics•May 18, 2025•0 citations

Probing the properties of quantum matter; an experimental study in three parts using ultracold atoms

Pieter C. Bons

The three experiments described in this thesis investigate fundamental properties of ultracold atoms. Using laser cooling and evaporative cooling, a dilute gas of sodium atoms is cooled to ~100 nK. Under these circumstances a Bose-Einstein condensate (BEC) forms, where millions of atoms collapse into the lowest energy state of the system and share a macroscopic wavefunction. The experiments are done in an ultrahigh vacuum and the atoms are manipulated remotely using laser beams, magnetic fields, and RF-fields. Using ultracold atoms allows unprecedented control over the internal and external degrees of freedom of the system, making it very suitable for precision measurements. Ultracold atoms also serve as a model system for more complicated or remote fields such as solid-state physics and cosmology. In the first experiment the refractive index of an ultracold bosonic gas is studied. The atomic clouds are analyzed for temperature and number of particles using nearly non-destructive phase-contrast imaging. After each pulse of probe light a small fraction of the atoms is lost, while the cloud is simultaneously slightly heated. This makes it possible to study the scattering rate as a function of temperature using only a single sample. It is observed that the scattering rate increases below the critical temperature for BEC by more than a factor of 3 compared to the classical value. This enhancement is in good agreement with the predictions by theoretical work that takes two-body correlation and the Lorentz-Lorenz correction into account. The method is also used to perform calorimetry on the Bose gas and directly measure the heat capacity of the BEC. The second chapter deals with magnetism in ultracold gases. When cooling an ultracold gas containing different spin components below the critical temperature for BEC, stable magnetic domains form. The appearance of these domains and the dynamics of the domain walls are studied. The spin mixture is prepared by performing an RF-sweep on ground state atoms in the presence of a magnetic field. Spin dynamics are induced by applying magnetic gradients. Spin drag, which is the transport coefficient responsible for damping spin currents, was measured in a two-component system. Furthermore a new method for spin resolved phase contrast imaging is presented, which is used to study time evolution in situ non-destructively. The last experiment focuses on spontaneous symmetry breaking. When passing a continuous phase transition, spontaneous symmetry breaking causes the development of domains with an independently chosen order parameter. The domains are separated by boundary defects. In this experiment the spontaneous creation of solitons was observed, which are boundary defects in the phase of the condensate, as well as magnetic domain walls, which are the boundary defects in the magnetization. Through the Kibble-Zurek mechanism it is possible to determine the critical exponents that characterize the phase transition. The critical exponents are predicted to be universal, i.e. do not depend on the microphysics of the system, so the results from our ultracold atoms lab can help answer universal questions for example from cosmology and from the early universe.

•May 13, 2015•0 citations
We propose a method to directly measure the complex phase distribution, superfluid density and velocity field in an ultracold atomic superfluid. The method consists of mapping the momentum distribution of the gas to real space using matterwave focusing, and manipulating the amplitude and phase by means of tailor made optical potentials. This makes it possible to find analogues of well-known techniques in optical microscopy such as Zernike phase contrast imaging, dark field imaging and schlieren imaging. Applying these ideas directly at the level of the macroscopic wavefunction of the superfluid will allow visualization of interesting effects such as phase fluctuations and topological defects, and enable measurements of transport properties such as vorticity.
We demonstrate and characterize an experimental technique to directly image the momentum distribution of a strongly interacting two-dimensional quantum gas with high momentum resolution. We apply the principles of Fourier optics to investigate three main operations on the expanding gas: focusing, collimation, and magnification. We focus the gas in the radial plane using a harmonic confining potential and thus gain access to the momentum distribution. We pulse a different harmonic potential to stop the rapid axial expansion, which allows us to image the momentum distribution with high resolution. Additionally, we propose a method to magnify the mapped momentum distribution to access interesting momentum scales. All these techniques can be applied to a wide range of experiments, and in particular to study many-body phases of quantum gases.
Detecting topological order in cold-atom experiments is an ongoing challenge, the resolution of which offers novel perspectives on topological matter. In material systems, unambiguous signatures of topological order exist for topological insulators and quantum Hall devices. In quantum Hall systems, the quantized conductivity and the associated robust propagating edge modes--guaranteed by the existence of nontrivial topological invariants--have been observed through transport and spectroscopy measurements. Here, we show that optical-lattice-based experiments can be tailored to directly visualize the propagation of topological edge modes. Our method is rooted in the unique capability for initially shaping the atomic gas and imaging its time evolution after suddenly removing the shaping potentials. Our scheme, applicable to an assortment of atomic topological phases, provides a method for imaging the dynamics of topological edge modes, directly revealing their angular velocity and spin structure.
Detecting topological order in cold-atom experiments is an ongoing challenge, the resolution of which offers novel perspectives on topological matter. In material systems, unambiguous signatures of topological order exist for topological insulators and quantum Hall devices. In quantum Hall systems, the quantized conductivity and the associated robust propagating edge modes - guaranteed by the existence of non-trivial topological invariants - have been observed through transport and spectroscopy measurements. Here, we show that optical-lattice-based experiments can be tailored to directly visualize the propagation of topological edge modes. Our method is rooted in the unique capability for initially shaping the atomic gas, and imaging its time-evolution after suddenly removing the shaping potentials. Our scheme, applicable to an assortment of atomic topological phases, provides a method for imaging the dynamics of topological edge modes, directly revealing their angular velocity and spin structure.
Coherence properties are central to quantum systems and are at the heart of phenomena such as superconductivity. In this work, we studied coherence properties of an ultracold Bose gas in a two-dimensional optical lattice across the thermal phase transition. To infer the phase coherence and phase fluctuation profiles, we used direct matter-wave imaging of higher Talbot revivals and introduced a phase microscope based on a site-resolved mapping of phase fluctuations to density fluctuations during matter-wave imaging. We observed the algebraic decay of the phase correlations in the superfluid phase and a linear temperature increase of the exponent. These techniques may enable studying coherence properties in strongly correlated quantum systems with full spatial resolution.
Abstract Ultracold atoms in optical lattices are a very promising quantum simulation platform, as they provide a very clean system (almost defect free) and allow control over many parameters such as tunneling coupling or interaction strength. Because the typical lattice spacing lies in the sub-micron range, it is technically demanding to resolve exactly the position of the atoms in the lattice using high-resolution optics such as quantum gas microscopy. Here we review the matter-wave protocol of quantum gas magnification that we developed for magnifying the atomic density distribution in the lattice (Asteria et al 2021 Nature 599 571). The atomic cloud, thus magnified by a factor of up to ∼ 90 , can then be imaged in a single-shot even with sub-lattice resolution with standard absorption imaging techniques. Furthermore, the protocol was demonstrated for 3D systems with high filling factors, which are typically impossible to measure with high-resolution imaging. In this tutorial, we will review how this technique can be used for high-resolution imaging of the density distribution and present the results obtained using it as a method to access new observables. We conclude with an outlook focusing on how this technique could be beneficial for a wide variety of physical systems which can be realized using cold atoms. This tutorial expands on the topic of my presentation for the SAMOP 2023 PhD Prize finalist symposium.
The three experiments described in this thesis investigate fundamental properties of ultracold atoms. Using laser cooling and evaporative cooling, a dilute gas of sodium atoms is cooled to ~100 nK. Under these circumstances a Bose-Einstein condensate (BEC) forms, where millions of atoms collapse into the lowest energy state of the system and share a macroscopic wavefunction. The experiments are done in an ultrahigh vacuum and the atoms are manipulated remotely using laser beams, magnetic fields, and RF-fields. Using ultracold atoms allows unprecedented control over the internal and external degrees of freedom of the system, making it very suitable for precision measurements. Ultracold atoms also serve as a model system for more complicated or remote fields such as solid-state physics and cosmology. In the first experiment the refractive index of an ultracold bosonic gas is studied. The atomic clouds are analyzed for temperature and number of particles using nearly non-destructive phase-contrast imaging. After each pulse of probe light a small fraction of the atoms is lost, while the cloud is simultaneously slightly heated. This makes it possible to study the scattering rate as a function of temperature using only a single sample. It is observed that the scattering rate increases below the critical temperature for BEC by more than a factor of 3 compared to the classical value. This enhancement is in good agreement with the predictions by theoretical work that takes two-body correlation and the Lorentz-Lorenz correction into account. The method is also used to perform calorimetry on the Bose gas and directly measure the heat capacity of the BEC. The second chapter deals with magnetism in ultracold gases. When cooling an ultracold gas containing different spin components below the critical temperature for BEC, stable magnetic domains form. The appearance of these domains and the dynamics of the domain walls are studied. The spin mixture is prepared by performing an RF-sweep on ground state atoms in the presence of a magnetic field. Spin dynamics are induced by applying magnetic gradients. Spin drag, which is the transport coefficient responsible for damping spin currents, was measured in a two-component system. Furthermore a new method for spin resolved phase contrast imaging is presented, which is used to study time evolution in situ non-destructively. The last experiment focuses on spontaneous symmetry breaking. When passing a continuous phase transition, spontaneous symmetry breaking causes the development of domains with an independently chosen order parameter. The domains are separated by boundary defects. In this experiment the spontaneous creation of solitons was observed, which are boundary defects in the phase of the condensate, as well as magnetic domain walls, which are the boundary defects in the magnetization. Through the Kibble-Zurek mechanism it is possible to determine the critical exponents that characterize the phase transition. The critical exponents are predicted to be universal, i.e. do not depend on the microphysics of the system, so the results from our ultracold atoms lab can help answer universal questions for example from cosmology and from the early universe.