Storing quantum information in a solid using dark-state polaritons

Johnsson, Mattias; Mølmer, Klaus

doi:10.1103/physreva.70.032320

Cited by 37 publications

(28 citation statements)

References 42 publications

(73 reference statements)

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“…The arguments of Ref. [24] were criticized in Ref. [7] but, to our knowledge, the question has not been fully resolved until now.…”

Section: Introductionmentioning

confidence: 99%

“…[24], the authors argued that, for successful operation in the quantum regime (i.e., when single atomic excitations are stored), the π pulses would have to be precise to order 1/N , where N is the number of atoms. Typically, solid-state ensembles contain order 10 7 to 10 9 atoms, and such a level of precision would thus be completely out of reach.…”

Section: Introductionmentioning

confidence: 99%

“…The argument of Ref. [24] was based on the fact that imperfect π pulses will lead to unwanted atomic excitations, which will cause background emissions. However, we will see that these emissions are noncollective and hence nondirectional.…”

Section: Introductionmentioning

confidence: 99%

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Precision requirements for spin-echo-based quantum memories

Heshami¹,

Sangouard²,

Minář³

et al. 2011

Phys. Rev. A

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Spin-echo techniques are essential for achieving long coherence times in solid-state quantum memories for light because of inhomogeneous broadening of the spin transitions. It has been suggested that unrealistic levels of precision for the radio-frequency control pulses would be necessary for successful decoherence control at the quantum level. Here we study the effects of pulse imperfections in detail, using both a semiclassical and a fully quantum-mechanical approach. Our results show that high efficiencies and low noise-to-signal ratios can be achieved for the quantum memories in the single-photon regime for realistic levels of control pulse precision. We also analyze errors due to imperfect initial-state preparation (optical pumping), showing that they are likely to be more important than control pulse errors in many practical circumstances. These results are crucial for future developments of solid-state quantum memories.

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“…The arguments of Ref. [24] were criticized in Ref. [7] but, to our knowledge, the question has not been fully resolved until now.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Precision requirements for spin-echo-based quantum memories

Heshami¹,

Sangouard²,

Minář³

et al. 2011

Phys. Rev. A

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“…However, whether this technique is applicable to the storage of quantum light or photons has not been resolved yet experimentally. The main concern [17,18] is that since the π pulses induce population inversion, tiny imperfection of them could result in background noises which are much stronger than the stored single-photon signals.In this letter we experimentally study the spin echo process of single excitations in a cold-atomic-gas quantum memory by employing stimulated Raman transitions. We find that the noise due to imperfection of the π pulses is highly directional.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Operating Spin Echo in the Quantum Regime for an Atomic-Ensemble Quantum Memory

et al. 2015

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Spin echo is a powerful technique to extend atomic or nuclear coherence time by overcoming the dephasing due to inhomogeneous broadening. However, applying this technique to an ensemblebased quantum memory at single-quanta level remains challenging. In our experimental study we find that noise due to imperfection of the rephasing pulses is highly directional. By properly arranging the beam directions and optimizing the pulse fidelities, we have successfully managed to operate the spin echo technique in the quantum regime and observed nonclassical photon-photon correlations. In comparison to the case without applying the rephasing pulses, quantum memory lifetime is extended by 5 folds. Our work for the first time demonstrates the feasibility of harnessing the spin echo technique to extend lifetime of ensemble-based quantum memories at single-quanta level. In an atomic-ensemble quantum memory, inhomogeneous broadening due to ambient magnetic field, atomic random motion and interaction with host spins etc. severely limits the storage time [12,13]. One universal solution to overcome inhomogeneous broadening induced decoherence is to make use of the spin echo technique [14], where a series of π pulses are applied to reverse the phase evolution through population inversion. This technique has been widely used in storage of classical light pulses. For example, with the spin echo technique, the storage lifetime has been extended to second and minute regime in solid-state ensembles and atomic-gas ensembles, respectively [15,16]. However, whether this technique is applicable to the storage of quantum light or photons has not been resolved yet experimentally. The main concern [17,18] is that since the π pulses induce population inversion, tiny imperfection of them could result in background noises which are much stronger than the stored single-photon signals.In this letter we experimentally study the spin echo process of single excitations in a cold-atomic-gas quantum memory by employing stimulated Raman transitions. We find that the noise due to imperfection of the π pulses is highly directional. In our experiment, by carefully arranging the Raman-beam directions and optimizing the pulse fidelities, we have successfully reduced this noise to much lower than the single-photon signal. Quantum nature of the spin echo process is verified by observing nonclassical photon-photon correlations. In our demonstration, the distorted spin-wave state gets rephased by applying two π pulses and the quantum memory lifetime is increased by 5 folds. Our findings and techniques developed is applicable to all other ensemblebased quantum memories [1].In an atomic-ensemble quantum memory, a single quantum state is stored as a spin wave spreading over the whole ensemble [19,20]. The spin-wave state at t = 0 can be described aswhere N is the number of atoms, |g and |s are two atomic ground states, k s is the wavevector of the spin wave, r j (0) is the position of the j-th atom in the ensemble at t = 0. This state can be physically interpreted as...

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Quantum Light Storage in Solid State Atomic Ensembles

Riedmatten

Afzelius

2015

Engineering the Atom-Photon Interaction

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In this chapter, we will describe the storage and retrieval of quantum light (heralded single photons and entangled photons) in atomic ensembles in a solid state environment. We will consider ensembles of rare-earth ions embedded in dielectric crystals. We will describe the methods used to create quantum light spectrally compatible with the narrow atomic transitions, as well as possible protocols based on dipole rephasing that can be used to reversibly map the quantum light onto collective atomic excitations. We will review the experimental state of the art and describe in more detail quantum light storage experiments in neodymium and praseodymium doped crystals.

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Storing quantum information in a solid using dark-state polaritons

Cited by 37 publications

References 42 publications

Precision requirements for spin-echo-based quantum memories

Precision requirements for spin-echo-based quantum memories

Operating Spin Echo in the Quantum Regime for an Atomic-Ensemble Quantum Memory

Quantum Light Storage in Solid State Atomic Ensembles

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