Optics and Interferometry with Atoms and Molecules

Schmiedmayer, Jörg; Chapman, Michael; Ekstrom, Christopher R.; Hammond, Tracy; Kokorowski, David A.; Lenef, Alan; Rubenstein, Richard A.; Smith, Edward T.; Pritchard, David E.

doi:10.1016/b978-012092460-8/50002-3

Cited by 35 publications

(99 citation statements)

References 126 publications

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“…(1), this would not constitute a violation of the LGI, as it represents an application of the concepts outside their proper realm of definition (i.e., non-dichotomic observables). Going further, the same principles could be used to test the LGI with electrons in free space, neutrons, atoms and molecules, all of which have had interference experiments in the MZI geometry conducted on them 80,81 . Of these, molecules offer the most exciting prospect, as there the nature of the coherence being tested could potentially be macroscopic, in line with the original goals of Ref.…”

Section: Discussionmentioning

confidence: 99%

Leggett-Garg inequality in electron interferometers

2012

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We consider the violation of the Leggett-Garg inequality in electronic Mach-Zehnder inteferometers. This set-up has two distinct advantages over earlier quantum-transport proposals: firstly, the required correlation functions can be obtained without time-resolved measurements. Secondly, the geometry of an interferometer allows one to construct the correlation functions from ideal negative measurements, which addresses the non-invasiveness requirement of the Leggett-Garg inequality. We discuss two concrete realisations of these ideas: the first in quantum Hall edge-channels, the second in a double quantum dot interferometer.PACS numbers: 03.65. Ud, 03.65.Ta, 42.50.Lc Bell inequalities set bounds on the nature of the correlations between spatially-separated entities within local hidden variable theories 1,2 . In contrast, Leggett-Garg inequalities (LGIs) set bounds on the temporal correlations of a single system 3,4 , and are derived under the assumptions of macroscopic realism (MR) and non-invasive measurability (NIM)5 . Bell and Leggett-Garg inequalities are related in that their assumptions both imply the existence of a classical probability distribution that determines experimental outcomes. The probability amplitudes of quantum mechanics allow for violation of these inequalities: with Bell, the violation is due to entanglement between the two systems; with Leggett-Garg, the violation occurs due to the superposition of system states and their collapse under measurement.The simplest LGI, henceforth referred to as the LGI, readswhereis the correlation function of the dichotomous variable Q = ±1 at times t α and t β . Since the first experimental violation 6 of this inequality with weak measurements of a superconducting qubit, the Leggett-Garg inequality has been experimentally probed in systems as diverse as photons 7-9 , defects in diamonds centers 10 , nuclear magnetic resonance 11 , and phosphorus impurities in silicon 12 . Whilst the subjects of these studies may not be macroscopic, the LGI performs a useful role for microscopic systems as an indicator that the device is operating beyond classical probability laws. Moreover, if one accepts that the alternative to classical probabilities is quantum mechanics, the LGI provides a decisive indicator of the "quantumness" on a system 13 . In this paper, we are interested in the violation of the LGI in quantum transport, and in particular, in electroninterferometers. Although there has been much work on Bell inequalities in electron transport, e.g. Refs 14-22, the LGI has only relatively recently been considered in this setting 23,24 . Specifically, the charge flowing through a confined nanostructure, e.g. double quantum dot (DQD), has been shown to violate an inequality similar to Eq. (1) out of equillibrium 23 . Furthermore, the moment-generating function of charge transferred through a device has also been shown to be subject to a set of LG-style inequalities, which are violated for various quantum dot models. The violation of LGIs in excitonic transport has ...

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Section: Discussionmentioning

confidence: 99%

Leggett-Garg inequality in electron interferometers

2012

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“…Our experimental setup is inspired by the sodium interferometer of D. Pritchard and co-workers [35] and by the metastable neon interferometer of Siu Au Lee and co-workers [12]. We are going to describe its main parts and to explain our procedures to align its components.…”

Section: Methodsmentioning

confidence: 99%

Lithium atom interferometer using laser diffraction: description and experiments

Miffre

Jacquey²,

Büchner³

et al. 2005

Eur. Phys. J. D

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We have built and operated an atom interferometer of the Mach-Zehnder type. The atomic wave is a supersonic beam of lithium seeded in argon and the mirrors and beam-splitters for the atomic wave are based on elastic Bragg diffraction on laser standing waves at λ = 671 nm. We give here a detailed description of our experimental setup and of the procedures used to align its components. We then present experimental signals, exhibiting atomic interference effects with a very high visibility, up to 84.5 ± 1 %. We describe a series of experiments testing the sensitivity of the fringe visibility to the main alignment defects and to the magnetic field gradient.

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“…-When we built our interferometer, we knew that D. Pritchard [17,19] and Siu Au Lee [18,21] had been obliged to reduce δ(t) in their atom interferometers by a servo-loop. Rather than using a servo-loop, we decided to improve the grating stability by building a very stiff rail.…”

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confidence: 99%

“…The inertial sensitivity of this type of interferometer is due to the existence of the diffraction phase which depends on the grating positions. The resulting phase of the interference signal is given by [19,20]:…”

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Phase noise due to vibrations in Mach-Zehnder atom interferometers

Jacquey

Miffre²,

Büchner

et al. 2006

Europhys. Lett.

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Abstract. -Atom interferometers are very sensitive to accelerations and rotations. This property, which has some very interesting applications, induces a deleterious phase noise due to the seismic noise of the laboratory and this phase noise is sufficiently large to reduce the fringe visibility in many experiments. We develop a model calculation of this phase noise in the case of Mach-Zehnder atom interferometers and we apply this model to our thermal lithium interferometer. We are able to explain the observed phase noise which has been detected through the rapid dependence of the fringe visibility with the diffraction order. We think that the dynamical model developed in the present paper should be very useful to reduce the vibration induced phase noise in atom interferometers, making many new experiments feasible.Introduction. -Atom interferometers are very sensitive to inertial effects [1, 2] and this property was used to build accelerometers [3-10] and gyrometers [11][12][13][14][15]. Because of this large sensitivity, a high mechanical stability of the experiment is required and several experiments [6,7,17,18] used an active control of the interferometer vibrations.In the present letter, we study the phase noise induced by mechanical vibrations in threegratings Mach-Zehnder thermal atom interferometers and we show that the rapid decrease of the fringe visibility with the diffraction order is largely due to this phase noise. Vibrations displace and bend the rail which holds the three diffraction gratings and we have developed a model based on elasticity theory to describe this dynamics. We are thus able to understand the contributions of various frequencies and to make a detailed evaluation of this phase noise in the case of our setup: the result is in good agreement with the phase noise value deduced from fringe visibility measurements. We have built a very stiff rail for our atom interferometer and this arrangement has revealed very efficient: the remaining phase noise is dominated by rotations of the rail, which should be reduced by a better rail suspension.

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Optics and Interferometry with Atoms and Molecules

Cited by 35 publications

References 126 publications

Leggett-Garg inequality in electron interferometers

Leggett-Garg inequality in electron interferometers

Lithium atom interferometer using laser diffraction: description and experiments

Phase noise due to vibrations in Mach-Zehnder atom interferometers

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