Photon Scattering from Atoms in an Atom Interferometer: Coherence Lost and Regained

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

doi:10.1103/physrevlett.75.3783

Cited by 238 publications

(234 citation statements)

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“…Experimental progress towards understanding decoherence has been made on a number of different fronts. One system that has the advantage of conceptual simplicity is a perturbed atom interferometer [2,3], where spontaneous scattering introduces dissipation into the system. Decoherence has also been observed with Rydberg atoms coupled to microwave cavities [4] and motional Schr€ o odinger cat states in an ion trap [5].…”

Section: Introductionmentioning

confidence: 99%

Timing noise effects on dynamical localization

Oskay

Steck

Raizen

2003

Chaos, Solitons & Fractals

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The quantum kicked rotor is studied experimentally in an atom-optics setting, where we observe the center-of-mass motion of cold cesium atoms. Dynamical localization in this system typically suppresses classical diffusive motion, but is susceptible to the addition of various forms of noise. We study in detail the effects of timing noise, where variations are introduced to the times at which the kicks occur. This noise is particularly interesting because it does not directly induce momentum diffusion. However, it is found that the addition of timing noise efficiently destroys both the classical correlations that give rise to fluctuations in the classical diffusion rate as well as quantum coherences that lead to dynamical localization. Ó 2002 Elsevier Science Ltd. All rights reserved.The interface between quantum and classical dynamics serves as a testing ground for decoherence and is a central feature of mesoscopic physics. It is believed that decoherence, the destruction of quantum interferences, is necessary to reconcile the distinctly different behavior in the quantum and classical limits [1]. Experimental progress towards understanding decoherence has been made on a number of different fronts. One system that has the advantage of conceptual simplicity is a perturbed atom interferometer [2,3], where spontaneous scattering introduces dissipation into the system. Decoherence has also been observed with Rydberg atoms coupled to microwave cavities [4] and motional Schr€ o odinger cat states in an ion trap [5].One of the most interesting settings in which to study correspondence is a classically chaotic system, where quantum effects suppress classical diffusive motion [6]. While the majority of research in decohering effects on ''quantum chaos'' has been theoretical in nature [7][8][9][10][11], there has been a steadily growing body of experimental work in recent years. Some of the pioneering experiments in this field have been conducted by studying the internal dynamics of Rydberg atoms [12][13][14][15]. Mesoscopic condensed-matter systems have provided another important testing ground [16]. Recent great advances in atom optics, the manipulation of atomic de Broglie waves, have also made it possible to study quantum dynamics by observing the center-of-mass motion of cold atoms [17,18]. Here, laboratory tests have allowed the direct observation of such phenomena as dynamical localization [19], quantum resonances [20], and chaos-assisted tunneling [21].Of particular interest is dynamical localization [22], a quantum suppression of classically chaotic (diffusive) motion. A prototypical system is the kicked rotor, or standard map, which has been a model system for the study of both classical and quantum chaos. The kicked rotor is a particularly suitable system for experimental study because it can be directly realized by exposing cold atoms to a pulsed standing wave of light. Classical particles in such a chaotic potential tend to exhibit diffusive behavior, where the energy of the system grows linearly as a f...

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Section: Introductionmentioning

confidence: 99%

Timing noise effects on dynamical localization

Oskay

Steck

Raizen

2003

Chaos, Solitons & Fractals

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“…Therefore the internal dynamics of the molecule is also relevant for the quantum behaviour of the centre-of-mass state. In contrast to resonance fluorescence, which was investigated with atoms [5][6][7], thermal decoherence is omnipresent in macroscopic systems and it cannot be switched off.FIG. 1: Set-up for the observation of thermal decoherence in a Talbot-Lau molecule interferometer.…”

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confidence: 99%

Decoherence of matter waves by thermal emission of radiation

Hackermüller

Hornberger

Brezger

et al. 2004

Nature

320

356

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Emergent quantum technologies have led to increasing interest in decoherence -the processes that limit the appearance of quantum effects and turn them into classical phenomena. One important cause of decoherence is the interaction of a quantum system with its environment, which 'entangles' the two and distributes the quantum coherence over so many degrees of freedom as to render it unobservable. Decoherence theory [1][2][3][4] has been complemented by experiments using matter waves coupled to external photons [5][6][7] or molecules [8], and by investigations using coherent photon states [9], trapped ions [10] and electron interferometers [11,12]. Large molecules are particularly suitable for the investigation of the quantumclassical transition because they can store much energy in numerous internal degrees of freedom; the internal energy can be converted into thermal radiation and thus induce decoherence. Here we report matter wave interferometer experiments in which C 70 molecules lose their quantum behaviour by thermal emission of radiation. We find good quantitative agreement between our experimental observations and microscopic decoherence theory. Decoherence by emission of thermal radiation is a general mechanism that should be relevant to all macroscopic bodies.In this Letter we investigate the decoherence of molecular matter waves. We change the internal temperature of the molecules in a controlled way before they enter a near-field interferometer, and observe the corresponding reduction of the interference contrast. The idea behind this effort is to demonstrate a most fundamental decoherence mechanism that we encounter in the macroscopic world: All large objects, but also molecules of sufficient complexity, are able to store energy and to interact with their environment via thermal emission of photons. It is generally believed that warm macroscopic bodies emit far too many photons to allow the observation of de Broglie interferences, whereas individual atoms or molecules can be sufficiently well isolated to exhibit their quantum nature. However, there must be a transition region between these two limiting cases. Interestingly, as we show in this study, C 70 fullerene molecules have just the right amount of complexity to exhibit perfect quantum interference in our experiments [13] at temperatures below 1000 K, and to gradually lose all their quantum behaviour when the internal temperature is increased up to 3000 K. We can thus trace the quantum-to-classical transition in a controlled and quantitative way. The complexity of large molecules adds a novel quality with respect to previously performed experiments with atoms [5][6][7]: the energy in molecules may be equilibrated in many internal degrees of freedom during the free flight, and a fraction of the vibrational energy will eventually be reconverted into emitted photons. Therefore the internal dynamics of the molecule is also relevant for the quantum behaviour of the centre-of-mass state. In contrast to resonance fluorescence, which was investigated wit...

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“…When the environment is a free field, we have 26) where N k is the number density of particles in the initial state of the quantum field (the above result is valid if the field is not free, in which case the propagators are appropriately dressed). This master equation is extremely rich.…”

Section: Example 3: Perturbative Master Equation For a Particle Intermentioning

confidence: 99%

“…As was also noted in the discussion of c-nots, [H AE ,Â] = 0 immediately implies thatÂ is a control, and its eigenstates will be preserved. Disappearance of quantum coherence because of a "one-bit" measurement has been verified experimentally in neutron and, more recently, in atomic interferometry [24][25][26]. A single act of quantum measurement we have discussed here should be regarded as an elementary discrete instance of continuous monitoring, which is required to bring about the appearance of classicality.…”

Section: One-bit Environment For a Bit-by-bit Measurementmentioning

confidence: 99%