Deterministic Single Photons via Conditional Quantum Evolution

Matsukevich, Dzmitry; Chanelière, Thierry; Jenkins, S. D.; Lan, Shau-Yu; Kennedy, Tom; Kuzmich, A.

doi:10.1103/physrevlett.97.013601

Cited by 125 publications

(144 citation statements)

References 39 publications

(58 reference statements)

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“…Furthermore, by repeated trials and feedback the entanglement generation can be made quasi-deterministic [24,25]. Our approach is related to other heralded schemes for quantum communication [24][25][26][27] and entangled-state preparation [28][29][30], and it would be interesting to generalize the present analysis to infer characteristics of the atomic state from the measured optical signals in those experiments. We note that the same first Dicke state was created in an ensemble of up to 41 atoms with a scheme that uses many heralding photons in a strongly coupled atom-cavity system [13].…”

mentioning

confidence: 96%

“…weak atom-photon coupling, heralding schemes can be used to boost the effective interaction strength by a large factor, enabling the production of highly entangled states [20,23]. Furthermore, by repeated trials and feedback the entanglement generation can be made quasi-deterministic [24,25]. Our approach is related to other heralded schemes for quantum communication [24][25][26][27] and entangled-state preparation [28][29][30], and it would be interesting to generalize the present analysis to infer characteristics of the atomic state from the measured optical signals in those experiments.…”

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confidence: 99%

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Entanglement with negative Wigner function of almost 3,000 atoms heralded by one photon

McConnell

Zhang

et al. 2015

Nature

212

218

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Quantum-mechanically correlated (entangled) states of many particles are of interest in quantum information, quantum computing and quantum metrology. Metrologically useful entangled states of large atomic ensembles have been experimentally realized [1][2][3][4][5][6][7][8][9][10], but these states display Gaussian spin distribution functions with a non-negative Wigner function. Non-Gaussian entangled states have been produced in small ensembles of ions [11,12], and very recently in large atomic ensembles [13][14][15]. Here, we generate entanglement in a large atomic ensemble via the interaction with a very weak laser pulse; remarkably, the detection of a single photon prepares several thousand atoms in an entangled state. We reconstruct a negative-valued Wigner function, an important hallmark of nonclassicality, and verify an entanglement depth (minimum number of mutually entangled atoms) of 2910 ± 190 out of 3100 atoms. This is the first time a negative Wigner function or the mutual entanglement of virtually all atoms have been attained in an ensemble containing more than a few particles. While the achieved purity of the state is slightly below the threshold for entanglement-induced metrological gain, further technical improvement should allow the generation of states that surpass this threshold, and of more complex Schrödinger cat states for quantum metrology and information processing. More generally, our results demonstrate the power of heralded methods for entanglement generation, and illustrate how the information contained in a single photon can drastically alter the quantum state of a large system.Entanglement is now recognized as a resource for secure communication, quantum information processing, and precision measurements. An important goal is the creation of entangled states of many-particle systems while retaining the ability to characterize the quantum state and validate entanglement. Entanglement can be verified in a variety of ways, with one of the strictest criteria being a negative-valued Wigner function [16,17], that necessarily implies that the entangled state has a non-Gaussian wavefunction. To date, the metrologically useful spin-squeezed states[1-10] have been produced in large ensembles. These states have Gaussian spin distributions and therefore can largely be modeled as systems with a classical source of spin noise, where quantum mechanics enters only to set the amount of Gaussian noise. Non-Gaussian states with a negative Wigner function, however, are manifestly non-classical, since the Wigner function as a quasiprobability function must remain nonnegative in the classical realm. While prior to this work a negative Wigner function had not been attained for atomic ensembles, in the optical domain, a negativevalued Wigner function has very recently been measured for states with up to 110 microwave photons [18]. Another entanglement measure is the entanglement depth [19], i.e. the minimum number of atoms that are demonstrably, but possibly weakly, entangled with one another. This paramete...

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confidence: 96%

mentioning

confidence: 99%

Entanglement with negative Wigner function of almost 3,000 atoms heralded by one photon

McConnell

Zhang

et al. 2015

Nature

212

218

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“…In the regime of continuous variables, a particularly notable advance has been the teleportation of quantum states between light and matter [14]. For discrete variables with photons taken one by one, important achievements include the efficient mapping of collective atomic excitations to single photons [15,16,17,18,19], the realization of entanglement between a pair of distant ensembles [5,20] In all these cases, progress has relied upon probabilistic schemes following the measurement-induced approach developed in the seminal paper by Duan, Lukin, Cirac and Zoller [4] (DLCZ ) and subsequent extensions. For the DLCZ protocol, heralded entanglement is generated by detecting a single photon emitted indistinguishably by one of two ensembles.…”

mentioning

confidence: 99%

“…In the regime of continuous variables, a particularly notable advance has been the teleportation of quantum states between light and matter [14]. For discrete variables with photons taken one by one, important achievements include the efficient mapping of collective atomic excitations to single photons [15,16,17,18,19], the realization of entanglement between a pair of distant ensembles [5,20] and, more recently, entanglement distribution involving two pairs of ensembles [6]. The first step toward entanglement swapping has been made [21] and lightmatter teleportation has been demonstrated [22].…”

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confidence: 99%

Mapping photonic entanglement into and out of a quantum memory

Choi

Deng

Laurat

et al. 2008

Nature

530

545

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Recent developments of quantum information science [1] critically rely on entanglement, an intriguing aspect of quantum mechanics where parts of a composite system can exhibit correlations stronger than any classical counterpart [2]. In particular, scalable quantum networks require capabilities to create, store, and distribute entanglement among distant matter nodes via photonic channels [3]. Atomic ensembles can play the role of such nodes [4]. So far, in the photon counting regime, heralded entanglement between atomic ensembles has been successfully demonstrated via probabilistic protocols [5,6]. However, an inherent drawback of this approach is the compromise between the amount of entanglement and its preparation probability, leading intrinsically to low count rate for high entanglement. Here we report a protocol where entanglement between two atomic ensembles is created by coherent mapping of an entangled state of light. By splitting a single-photon [7,8,9] and subsequent state transfer, we separate the generation of entanglement and its storage [10]. After a programmable delay, the stored entanglement is mapped back into photonic modes with overall efficiency of 17%. Improvements of single-photon sources [11] together with our protocol will enable "on-demand" entanglement of atomic ensembles, a powerful resource for quantum networking.In the quest to achieve quantum networks over long distances [3], an area of considerable activity has been the interaction of light with atomic ensembles comprised of a large collection of identical atoms [4,12,13]. In the regime of continuous variables, a particularly notable advance has been the teleportation of quantum states between light and matter [14]. For discrete variables with photons taken one by one, important achievements include the efficient mapping of collective atomic excitations to single photons [15,16,17,18,19], the realization of entanglement between a pair of distant ensembles [5,20] In all these cases, progress has relied upon probabilistic schemes following the measurement-induced approach developed in the seminal paper by Duan, Lukin, Cirac and Zoller [4] (DLCZ ) and subsequent extensions. For the DLCZ protocol, heralded entanglement is generated by detecting a single photon emitted indistinguishably by one of two ensembles. Intrinsically, the probability p to prepare entanglement with only 1 excitation shared between two ensembles is related to the quality of entanglement, since the likelihood for contamination of the entangled state by processes involving 2 excitations scales as p [20], and results in low success probability for each trial. Although the degree of stored entanglement can approach unity for the (rare) successful trials [20], the condition p ≪ 1 dictates reductions in count rate and compromises in the quality of the resulting entangled state (e.g., as p → 0, processes such as stray light scattering and detector dark counts become increasingly important). Furthermore, for finite memory time, subsequent connection of entanglement become...

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“…However, we note that owing to the low success probability of teleportation and the short lifetime of quantum memory, significant improvements are still needed for our method to be useful for practical applications. For example, we could use active feedforward to achieve both a deterministic entanglement source 3-5 and a high-quality single-photon source 25,26 , by which the overall success of the teleportation rate can be greatly increased while the spurious coincidence is suppressed. This, given our present excitation rate of anti-Stokes photons, would require a lifetime of quantum memory up to 1 ms.…”

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confidence: 99%

Memory-built-in quantum teleportation with photonic and atomic qubits

et al. 2008

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The combination of quantum teleportation 1 and quantum memory 2-5 of photonic qubits is essential for future implementations of large-scale quantum communication 6 and measurement-based quantum computation 7,8 . Both steps have been achieved separately in many proof-of-principle experiments 9-14 , but the demonstration of memory-built-in teleportation of photonic qubits remains an experimental challenge. Here, we demonstrate teleportation between photonic (flying) and atomic (stationary) qubits. In our experiment, an unknown polarization state of a single photon is teleported over 7 m onto a remote atomic qubit that also serves as a quantum memory. The teleported state can be stored and successfully read out for up to 8 µs. Besides being of fundamental interest, teleportation between photonic and atomic qubits with the direct inclusion of a readable quantum memory represents a step towards an efficient and scalable quantum network 2-8 .Quantum teleportation 1 , a way to transfer the state of a quantum system from one place to another, was first demonstrated between two independent photonic qubits 9 ; later developments include demonstration of entanglement swapping 10 , open-destination teleportation 11 and teleportation between two ionic qubits 15,16 . Teleportation has also been demonstrated for a continuous-variable system, that is, transferring a quantum state from one light beam to another 17 and, more recently, even from light to matter 18 . However, the above demonstrations have several drawbacks, especially in long-distance quantum communication. On the one hand, the absence of quantum storage makes the teleportation of light alone non-scalable. On the other hand, in teleportation of ionic qubits, the shared entangled pairs were created locally, which limits the teleportation distance to a few micrometres and is difficult to extend to large distances. In continuous-variable teleportation between light and matter, the experimental fidelity is extremely sensitive to the transmission loss-even in the ideal case, only a maximal attenuation of 10 −1 is tolerable 19 . Moreover, the complicated protocol required for retrieving the teleported state in the matter 20 is beyond the reach of current technology.The combination of quantum teleportation and quantum memory of photonic qubits 2-5 could provide a novel way to overcome these drawbacks. Here, we achieve this appealing combination by experimentally implementing teleportation between discrete photonic (flying) and atomic (stationary) qubits.In our experiment, we use the polarized photonic qubits as the information carriers and the collective atomic qubits [2][3][4][5]12 (an effective qubit consists of two atomic ensembles, each with 10 6 rubidium-87 atoms) as the quantum memory. In memorybuilt-in teleportation, an unknown polarization state of single photons is teleported onto and stored in a remote atomic qubit via a Bell-state measurement between the photon to be teleported and the photon that is originally entangled with the atomic qubit. The protocol has ...

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Deterministic Single Photons via Conditional Quantum Evolution

Cited by 125 publications

References 39 publications

Entanglement with negative Wigner function of almost 3,000 atoms heralded by one photon

Entanglement with negative Wigner function of almost 3,000 atoms heralded by one photon

Mapping photonic entanglement into and out of a quantum memory

Memory-built-in quantum teleportation with photonic and atomic qubits

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