Attractive photons in a quantum nonlinear medium

Firstenberg, Ofer; Peyronel, Thibault; Liang, Qiyu; Gorshkov, Alexey V.; Lukin, Mikhail D.; Vuletić, Vladan

doi:10.1038/nature12512

Cited by 418 publications

(525 citation statements)

References 31 publications

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“…Complementary work pointed to the possibility of few-photon bound states [82][83][84] , although the weak nonlinearities associated with fibres made their physical realization unrealistic at the time. Only very recently have such two-photon bound states been observed experimentally in Rydberg EIT 72 (Fig. 5).…”

Section: Many-body Physics With Strongly Interacting Photonsmentioning

confidence: 99%

“…In this case, the photons not only travel slowly, but also acquire an effective mass owing to group-velocity dispersion. The attractive interaction between photons in a one-dimensional system then supports a bound state of two photons that manifests itself in the form of photon bunching at the system exit 72 (Fig. 5).…”

Section: Quantum Nonlinear Optics Through Atom-atom Interactionsmentioning

confidence: 99%

“…This implies that two photons can experience an effective distance-dependent potential and force. Firstenberg and co-workers recently implemented such a situation by means of detuned EIT 72 , whereby the control laser is detuned from resonance with the intermediate state, but the two-photon resonance with probe and control laser to the Rydberg state is maintained. In this case, the photons not only travel slowly, but also acquire an effective mass owing to group-velocity dispersion.…”

Section: Quantum Nonlinear Optics Through Atom-atom Interactionsmentioning

confidence: 99%

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Quantum nonlinear optics — photon by photon

2014

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other. This linearity in light propagation, in combination with the high frequency and hence large bandwidth provided by waves at optical frequencies, has made optical signals the preferred method for communicating information over long distances. In contrast, the processing of information requires some form of interaction between signals. In the case of light, such interactions can be enabled by nonlinear optical processes. These processes, which are now found ubiquitously throughout science and technology, include optical modulation and switching, nonlinear spectroscopy and frequency conversion 1 , and have applications across both the physical 2 and biological 3,4 sciences.A long-standing goal in optical science has been the implementation of nonlinear effects at progressively lower light powers or pulse energies. The ultimate limit may be termed 'quantum nonlinear optics' (Box 1) -the regime where individual photons interact so strongly with one another that the propagation of light pulses containing one, two or more photons varies substantially with photon number. Although this domain is difficult to reach owing to the small nonlinear coefficients of bulk optical materials, the potential payoff is significant. The realization of quantum nonlinear optics could improve the performance of classical nonlinear devices, enabling, for example, fast energy-efficient optical transistors that avoid Ohmic heating 5 . Furthermore, nonlinear switches activated by single photons could enable optical quantum information processing and communication 6 , as well as other applications that rely on the generation and manipulation of non-classical light fields 7,8 . The challenge of making photons interactAt low optical powers, most optical materials exhibit only linear optical phenomena, such as refraction and absorption, which can be described by a complex index of refraction. However, a sufficiently intense light beam can modify a material's index of refraction, such that the light propagation becomes power-dependent. This is the essence of classical nonlinear optics (Box 1). Large optical fields are required to alter the index of refraction of conventional bulk materials because a strong nonlinear response can only be induced if the electric field of the light beam acting on the electrons is comparable to the field of the nucleus. As a result, early experimental observations of nonlinear optical phenomena, such as frequencydoubling or sum-frequency generation 9 , were achievable only after the development of powerful lasers. Advances in nonlinear optics over the past four decades have resulted in progressively more efficient nonlinear processes 10 , thus enabling the observation of nonlinear processes at lower and lower light levels. It is natural to inquire if and how these nonlinear interactions can be made so strong that they become important even at the level of individual quanta of radiation. Although this question was addressed in early theoretical studies [11][12][13] , it has become more pressing with the advent of...

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Section: Many-body Physics With Strongly Interacting Photonsmentioning

confidence: 99%

Section: Quantum Nonlinear Optics Through Atom-atom Interactionsmentioning

confidence: 99%

Section: Quantum Nonlinear Optics Through Atom-atom Interactionsmentioning

confidence: 99%

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Quantum nonlinear optics — photon by photon

2014

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“…In particular, implementations of quantum repeaters will likely rely on mapping of photonic states onto atomic systems to enable storage of quantum information [3,4]. Deterministic quantum logic gates in optical systems may also rely on atomic state mapping to enable nonlinear photon-photon interactions [5,6,7,8,9]. A fundamental issue facing any attempt to implement nonlinear cross phase modulation (XPM) is that the interaction is inherently very weak.…”

Section: Introductionmentioning

confidence: 99%

Dynamical observations of self-stabilizing stationary light

Everett¹,

Campbell²,

Cho³

et al. 2016

Nature Phys

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Precise control of atom-light interactions is vital to many quantum information protocols. In particular, atomic systems can be used to slow and store light to form a quantum memory. Optical storage can be achieved via stopped light, where no optical energy remains in the atoms, or as stationary light, where some optical energy remains present during storage. In this work, we demonstrate a form of self-stabilising stationary light. From any initial state, our atom-light system evolves to a stable configuration that is devoid of coherent emission from the atoms, yet may contain bright optical excitation. This phenomenon is verified experimentally in a cloud of cold Rb87 atoms. The spinwave in our atomic cloud is imaged from the side allowing direct comparison with theoretical predictions.Coherent atom light interactions lie at the heart of many quantum information systems [1, 2]. In particular, implementations of quantum repeaters will likely rely on mapping of photonic states onto atomic systems to enable storage of quantum information [3,4]. Deterministic quantum logic gates in optical systems may also rely on atomic state mapping to enable nonlinear photon-photon interactions [5,6,7,8,9]. A fundamental issue facing any attempt to implement nonlinear cross phase modulation (XPM) is that the interaction is inherently very weak. Techniques are therefore required to increase the interaction time or interaction strength to allow useful amounts of phase shift. Interaction strength can be scaled up by choosing a nonlinear medium with strong optical interactions, such as Rydberg atoms [10,11]. A more general approach that works for any medium is to use smaller interaction volumes, since this increases the electric field per photon, and longer interaction times, which may be achieved by using an 1 arXiv:1609.08287v1 [quant-ph]

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“…There is a significant body of work studying the effects of mapping photons onto collective atomic Rydberg excitations [14][15][16][17][18][19][20]. Most proposals for photon-photon gates involve propagating Rydberg excitations (polaritons), either using blockade [21,22] or two excitations [23][24][25][26].…”

mentioning

confidence: 99%

Photon-photon gate via the interaction between two collective Rydberg excitations

Khazali

Heshami²,

Simon³

2015

Phys. Rev. A

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We propose a scheme for a deterministic controlled-phase gate between two photons based on the strong interaction between two stationary collective Rydberg excitations in an atomic ensemble. The distance-dependent character of the interaction causes both a momentum displacement of the collective excitations and unwanted entanglement between them. We show that these effects can be overcome by swapping the collective excitations in space and by optimizing the geometry, resulting in a photon-photon gate with high fidelity and efficiency.Deterministic quantum gates between individual photons are very desirable for photonic quantum information processing [1][2][3][4][5]. As photons interact only very weakly in free space, the implementation of such gates requires appropriate media. One attractive approach involves converting the photons into atomic excitations in highly excited Rydberg states, which exhibit strong interactions. Rydberg state based quantum gates between individual atoms and between atomic ensembles have been proposed [6][7][8][9][10] and implemented [11][12][13]. There are two categories of gates, those relying on the interaction between two excited atoms [6,7], and those based on Rydberg blockade [7][8][9][10][11][12][13], where only one atom is excited at any given time. There is a significant body of work studying the effects of mapping photons onto collective atomic Rydberg excitations [14][15][16][17][18][19][20]. Most proposals for photon-photon gates involve propagating Rydberg excitations (polaritons), either using blockade [21,22] or two excitations [23][24][25][26].Separating the interaction process and propagation makes it easier to achieve high fidelities for these photonic gates [27]. Such separation can be achieved by photon storage, i.e. by converting the photons into stationary rather than moving atomic excitations. The only storagebased photonic gate that has been proposed so far is based on the blockade effect [27]. Achieving blockade conditions can be challenging since both photons have to be localized within the blockade volume. Following [6,7,[23][24][25][26], we here propose a storage-based scheme that instead relies on the interaction between two stationary Rydberg excitations.The main challenge for two-excitation based Rydberg gates in atomic ensembles arises from the fact that the interaction is strongly distance-dependent and thus not uniform over the profiles of the two stored photons. We show that this a priori reduces the gate's fidelity by displacing the collective excitations in momentum space and by entangling their quantum states. However, we then show that it is possible to completely compensate the first effect by swapping the collective excitations in the middle of the interaction time, and to greatly alleviate the second effect by optimizing the shape and separation of the excitations, resulting in a photon-photon gate that achieves both high fidelity and high efficiency. Now we describe our scheme in detail. As shown in Fig. 1a, information is encoded in dual-rail...

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Attractive photons in a quantum nonlinear medium

Cited by 418 publications

References 31 publications

Quantum nonlinear optics — photon by photon

Quantum nonlinear optics — photon by photon

Dynamical observations of self-stabilizing stationary light

Photon-photon gate via the interaction between two collective Rydberg excitations

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