<i>In situ</i> magnetometry for experiments with atomic quantum gases

Krinner, Ludwig; Stewart, Michael H.; Pazmino, Arturo; Schneble, Dominik

doi:10.1063/1.5003646

Cited by 4 publications

(3 citation statements)

References 23 publications

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“…The dispersive nature of the measurement technique applied allows it to be conducted in sequence with other experiments on cold atoms. This concept was recently demonstrated in [22] and in the context of magnetometry in [32]. Our setup is equipped to create arrays of tweezers that can be individually probed without disturbing the atoms in neighbouring traps.…”

Section: Discussionmentioning

confidence: 99%

“…Most notably, the single-shot precision is better than typical shot-to-shot fluctuations, which renders the method eligible for improving measurements of atomic properties that depend crucially on the background magnetic field. In such cases one must measure the background field during the experiment and either actively compensate for its effect [32] or post select from the data according to the value measured [22,33].…”

Section: Vectorial Magnetometrymentioning

confidence: 99%

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Spatially-selective in situ magnetometry of ultracold atomic clouds

Elíasson

Heck

Laustsen

et al. 2019

J. Phys. B: At. Mol. Opt. Phys.

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We demonstrate novel implementations of high-precision optical magnetometers which allow for spatially-selective and spatially-resolved in situ measurements using cold atomic clouds. These are realised by using shaped dispersive probe beams combined with spatially-resolved balanced homodyne detection. Two magnetometer sequences are discussed: a vectorial magnetometer, which yields sensitivities two orders of magnitude better compared to a previous realisation and a Larmor magnetometer capable of measuring absolute magnetic fields. We characterise the dependence of single-shot precision on the size of the analysed region for the vectorial magnetometer and provide a lower bound for the measurement precision of magnetic field gradients for the Larmor magnetometer. Finally, we give an outlook on how dynamic trapping potentials combined with selective probing can be used to realise enhanced quantum simulations in quantum gas microscopes.

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Section: Discussionmentioning

confidence: 99%

Section: Vectorial Magnetometrymentioning

confidence: 99%

Spatially-selective in situ magnetometry of ultracold atomic clouds

Elíasson

Heck

Laustsen

et al. 2019

J. Phys. B: At. Mol. Opt. Phys.

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“…This methodology may also find applications for fluctuating magnetic fields in the determination of magnetic order phase transitions in Ising spin chains [4], impurity doping concentrations for the quantum simulation of the doped Hubbard Hamiltonian [32,33], or the chemical potential in the realization of both Bose-and Fermi-Hubbard models. Recently, post-selection of data conditioned on in-sequence insitu measurements of magnetic field values was used to enhance Rabi oscillation contrast [34].In Sec. II of this article, we perform a detailed comparison arXiv:1607.02934v2 [quant-ph]…”

mentioning

confidence: 99%

Measurement-enhanced determination of BEC phase transitions

Bason¹,

Heck²,

Napolitano³

et al. 2018

J. Phys. B: At. Mol. Opt. Phys.

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We demonstrate how dispersive atom number measurements during evaporative cooling can be used for enhanced determination of the parameter dependence of the transition to a Bose-Einstein condensate (BEC). In this way shot-to-shot fluctuations in initial conditions are detected and the information extracted per experimental realization is increased. We furthermore calibrate in-situ images from dispersive probing of a BEC with corresponding absorption images in time-of-flight. This allows for the determination of the transition point in a single experimental realization by applying multiple dispersive measurements. Finally, we explore the continuous probing of several consecutive phase transition crossings using the periodic addition of a focused "dimple" potential.Quantum effects have become increasingly important in the development of modern technologies and have led to the need for accurate quantum simulation [1,2]. Various approaches, including cold atoms [3-5] and ions [6], superconducting circuits [7], and photons [8] are used to perform such simulations. In particular, many quantum simulators aim to pin down the boundaries between discrete phases of many-body systems, such as Ising spin transition points [4,6] or magnetic phases [5], with the highest possible accuracy. Current simulations focus on providing tight experimental bounds for benchmarking theoretical models, such as finite temperature bosonic superfluids in optical lattices [9].In this article we investigate the potential for using dispersive probing of ultracold atom clouds in two distinct toymodel settings to enhance future quantum simulations. First, we demonstrate that benchmark probes of thermal clouds during forced evaporative cooling can be used to enhance the accuracy in determining the critical point, at which the transition to a Bose-Einstein condensate (BEC) occurs. Second, we investigate multiple, in-situ probing of BECs during evaporation as a means of single-shot mapping of a phase transition.Since the pioneering work on dispersive probing [10,11], it has been employed to investigate the relative repulsion of BECs and thermal clouds [12] and to monitor the formation of a BEC [13,14] as well as the appearance and dynamics of solitons [15,16]. In-sequence benchmark measurements of cold atomic clouds have recently been applied as a tool to moderately reduce classical fluctuations in atom number [17]. Using active feedback, atom number stabilization of cold clouds to the 10 −3 level was demonstrated in Ref. [18]. However, to date no experiments have explored benchmark-measurement enhanced evaluation of the BEC atom number. Efficient suppression of classical fluctuations could enable the settlement of long-standing theoretical disputes concerning the nature * M. G. Bason and R. Heck contributed equally to this work † Electronic address: sherson@phys.au.dk of fundamental fluctuations arising at the BEC phase transition [19]. In recent years, theoretical studies on dispersive lightmatter interaction based Quantum Non-Demolition (QND) measure...

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Spontaneous emission of matter waves from a tunable open quantum system

Krinner

Stewart

Pazmino

et al. 2018

Nature

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125

113

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The decay of an excited atom undergoing spontaneous photon emission into the fluctuating quantum-electrodynamic vacuum is an emblematic example of the dynamics of an open quantum system. Recent experiments have demonstrated that the gapped photon dispersion in periodic structures, which prevents photons in certain frequency ranges from propagating, can give rise to unusual spontaneous-decay behaviour, including the formation of dissipative bound states. So far, these effects have been restricted to the optical domain. Here we demonstrate similar behaviour in a system of artificial emitters, realized using ultracold atoms in an optical lattice, which decay by emitting matter-wave, rather than optical, radiation into free space. By controlling vacuum coupling and the excitation energy, we directly observe exponential and partly reversible non-Markovian dynamics and detect a tunable bound state that contains evanescent matter waves. Our system provides a flexible platform for simulating open-system quantum electrodynamics and for studying dissipative many-body physics with ultracold atoms.

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In situ magnetometry for experiments with atomic quantum gases

Cited by 4 publications

References 23 publications

Spatially-selective in situ magnetometry of ultracold atomic clouds

Spatially-selective in situ magnetometry of ultracold atomic clouds

Measurement-enhanced determination of BEC phase transitions

Spontaneous emission of matter waves from a tunable open quantum system

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