Highly-efficient quantum memory for polarization qubits in a spatially-multiplexed cold atomic ensemble

Vernaz-Gris, Pierre; Huang, Kun; Cao, Mingtao; Sheremet, A. S.; Laurat, Julien

doi:10.1038/s41467-017-02775-8

Cited by 168 publications

(124 citation statements)

References 52 publications

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“…1(c). To store the polarization qubit state in the two-dimensional Hilbert space, we take the spatially-multiplexed dual-rail scheme 14 to convert the two polarization basis |H and |V into two spatial modes which can be stored simultaneously in the memory. As shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…A photonic memory is built on the light-matter interface between flying photonic modes and long-lived matter states. Efficient optical storages have been demonstrated in various promising schemes, such as 87% efficiency with photon echo technique 8,9 , 30% with off-resonance Raman interaction 10,11 , and 92% with electromagnetically induced transparency (EIT) [12][13][14][15] . However all these experimental demonstrations have been performed with attenured weak coherent laser pulses.…”

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confidence: 99%

“…As a result, the highest efficiency records are 49% for the single-photon temporal waveform 17 , 10% for single-photon polarization qubit 18 , and 26.7% for entanglement 19,20 . Boosting up the memory efficiency is crucial to make the quantum memory practical 3,9,14,15,21 . For example, a 1% increase in the memory efficiency would increase the entanglement distribution rate by a value beyond 10% in the repeater-based quantum network 3, 21 .…”

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Efficient quantum memory for single-photon polarization qubits

et al. 2019

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A quantum memory, for storing and retrieving flying photonic quantum states, is a key interface for realizing long-distance quantum communication and large-scale quantum computation. While many experimental schemes of high storage-retrieval efficiency have been performed with weak coherent light pulses, all quantum memories for true single photons achieved so far have efficiencies far below 50%, a threshold value for practical applications. Here, we report the demonstration of a quantum memory for single-photon polarization qubits with an efficiency of >85% and a fidelity of >99%, basing on balanced two-channel electromagnetically induced transparency in laser-cooled rubidium atoms. For the singlechannel quantum memory, the optimized efficiency for storing and retrieving single-photon temporal waveforms can be as high as 90.6%. Our result pushes the photonic quantum memory closer to its practical applications in quantum information processing.

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Section: Resultsmentioning

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Efficient quantum memory for single-photon polarization qubits

et al. 2019

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“…Cold atomic gases are currently one of the best quantum memory platforms with excellent properties demonstrated, including single photon storage and retrieval efficiency up to 90 % [4][5][6][7][8] and storage time up to 220 ms [5,9]. In particular, this system is well suited for realizing a photon pair source with embedded quantum memory following the Duan-Lukin-Cirac-Zoller protocol [10], that can be used as a quantum repeater node [11][12][13].…”

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A cold-atom temporally-multiplexed quantum repeater node with cavity-enhanced noise suppression (Conference Presentation)

Heller

Farrera

Heinze

et al. 2020

Quantum Technologies 2020

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Future quantum repeater architectures, capable of efficiently distributing information encoded in quantum states of light over large distances, will benefit from multiplexed photonic quantum memories. In this work we demonstrate a temporally multiplexed quantum repeater node in a laser-cooled cloud of 87 Rb atoms. We employ the DLCZ protocol where pairs of photons and single collective spin excitations (so called spin waves) are created in several temporal modes using a train of write pulses. To make the spin waves created in different temporal modes distinguishable and enable selective readout, we control the dephasing and rephasing of the spin waves by a magnetic field gradient, which induces a controlled reversible inhomogeneous broadening of the involved atomic hyperfine levels. We demonstrate that by embedding the atomic ensemble inside a low finesse optical cavity, the additional noise generated in multi-mode operation is strongly suppressed. By employing feed forward readout, we demonstrate distinguishable retrieval of up to 10 temporal modes. For each mode, we prove non-classical correlations between the first and second photon. Furthermore, an enhancement in rates of correlated photon pairs is observed as we increase the number of temporal modes stored in the memory. The reported capability is a key element of a quantum repeater architecture based on multiplexed quantum memories.Quantum light-matter interfaces are key platforms in the field of quantum information. They provide storage, processing or synchronization of photonic quantum states, which can be used for applications in quantum communication, computation or sensing [1, 2]. One example is optical quantum memories, devices able to store and retrieve photonic quantum states. Multiplexed optical quantum memories are important in order to achieve higher data communication rates, as it is similarly done in conventional classical communications. One particularly interesting application of multiplexed quantum memories is to enhance the entanglement distribution rate in quantum repeaters [3], which in turn also facilitate their practical realization by relaxing the storage time requirements. For this application, the quantum memory should be able to store a large number of distinguishable modes and to read them out selectively. Different degrees of freedom have been considered for the multiplexed modes, such as frequency, space or time. Ensemble-based platforms, where photonic quantum information is mapped onto collective atomic excitations, are well suited for demonstrating quantum information multiplexing.Cold atomic gases are currently one of the best quantum memory platforms with excellent properties demonstrated, including single photon storage and retrieval efficiency up to 90 % [4-8] and storage time up to 220 ms [5,9]. In particular, this system is well suited for realizing a photon pair source with embedded quantum memory following the Duan-Lukin-Cirac-Zoller protocol [10], that can be used as a quantum repeater node [11][12][13]. Current multi...

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“…In the future, our multiplexed atom-cavity system may be combined with nonlinear cavity-mediated interactions or quantum nondemolition measurements that would enable universal quantum operations between spin waves. The demonstration here, of spin-wave multiplexed cavity electrodynamics, is a significant step toward these goals.Our apparatus is complementary to an active body of ensemble multiplexing research, using both spatial and spectral degrees of freedom [13][14][15][16][17][18][19][20][21][22][23]. Recently, a spatial array of single-photon detectors has been used to resolve 665 independent spin waves in an atomic ensemble [24,25].…”

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confidence: 99%

Spin-Wave Multiplexed Atom-Cavity Electrodynamics

et al. 2019

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We introduce multiplexed atom-cavity quantum electrodynamics with an atomic ensemble coupled to a single optical cavity mode. Multiple Raman dressing beams establish cavity-coupled spinwave excitations with distinctive spatial profiles. Experimentally, we demonstrate the concept by observing spin-wave vacuum Rabi splittings, selective superradiance, and interference in the cavitymediated interactions of two spin waves. We highlight that the current experimental configuration allows rapid, interchangeable cavity-coupling to 4 profiles with an overlap parameter of less than 10%, enough to demonstrate, for example, a quantum repeater network simulation in the cavity. With further improvements to the optical multiplexing setup, we infer the ability to access more than 10 3 independent spin-wave profiles.Significant resources are now being devoted to develop intermediate scale quantum systems with tens or hundreds of quantum bits, tunable interactions, and independent control of each element. Ion traps [1], superconducting circuits [2], tweezer arrays of neutral atoms [3], and other systems have made exciting recent advances, but scaling precise quantum dynamics from few-body to many-body remains as a primary challenge in quantum science.Instead of building up qubit-by-qubit, like the aforementioned platforms, here we focus on a system where quantum information is stored as patterns or images inside a single cavity-coupled atomic ensemble containing up to 10 6 atoms. This scalability more closely resembles, for example, that of a neural network, where data is stored and manipulated as patterns and images rather than binary bits [4][5][6][7].In this Letter, we introduce an apparatus that allows creation of multiple spin-wave excitations with unique spatial profiles. The spin waves are all collectively enhanced to emit into a single TEM00 cavity mode, and cavity coupling of each spin wave is dynamically controlled using a corresponding Raman dressing beam, generated by a two-dimensional acousto-optic deflector. Experimentally, we first observe strong spin wave/cavity interactions by measuring a dressed-state vacuum Rabi splitting (VRS) associated with the spin-wave Raman transition. Second, we discuss how spin waves are protected from cross-talk through collective dephasing, and demonstrate a high degree of distinguishability by observing selective superradiance over the continuum of spin-wave profiles. Finally, we observe interference as two spin-waves simultaneously interact with the cavity mode.As a multiplexed atom-cavity interface [8], our system may form the building block of a scalable quantum repeater [9]. Alternatively, this approach opens an elegant avenue to demonstrate a local bosonic quantum network for efficiently simulating many-body physics [10-12], generating samples from exponentially complex wave functions, or performing entanglement-enhanced or error-corrected quantum sensing. In the future, our multiplexed atom-cavity system may be combined with nonlinear cavity-mediated interactions or quantum nond...

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Highly-efficient quantum memory for polarization qubits in a spatially-multiplexed cold atomic ensemble

Cited by 168 publications

References 52 publications

Efficient quantum memory for single-photon polarization qubits

Efficient quantum memory for single-photon polarization qubits

A cold-atom temporally-multiplexed quantum repeater node with cavity-enhanced noise suppression (Conference Presentation)

Spin-Wave Multiplexed Atom-Cavity Electrodynamics

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