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European Quantum Electronics Conference (EQEC)

A Solid State Spin-Wave Quantum Memory for Photonic Time-Bin Qubits

Mustafa Gündoğan, Kutlu Kutluer, Patrick M. Ledingham, Margherita Mazzera, Hugues de Riedmatten

Published Jun 21, 2015• 0 citations
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Abstract

Rare-earth (RE) doped crystals are promising candidates as quantum memories as they offer coherence properties comparable to those of atomic systems, but free of the drawbacks deriving from the atomic motion. The research on RE doped crystals quantum memories has been so far mostly focused on the mapping of quantum bits to optical collective excitations using the atomic frequency comb (AFC) or the gradient echo memory protocols [1-3]. However, this leads to short lived and mostly pre-determined storage. In this contribution, we report the first solid state spin-wave optical quantum memory with on-demand read-out. We also demonstrate the first spin-wave storage of time-bin qubits with conditional fidelities higher than for classical memories [4].

Related papers

Solid-state spin-wave quantum memories for single photons (Conference Presentation)

Hugues de Riedmatten

Photonic quantum memories are important devices in quantum information science, and are crucial for several applications including quantum repeaters and quantum networks. Rare-earth (RE) doped crystals are promising candidates as quantum memories for light as they offer coherence properties comparable to those of atomic systems, but free of the drawbacks deriving from atomic motion. The research on RE based quantum memories has been so far mostly focused on the mapping of photonic quantum bits to optical collective excitations, but this leads to short lived and mostly pre-determined storage. However, some RE ions, as Praseodymium and Europium, exhibit the suitable energy level scheme, with three long-lived hyperfine ground states, to enable the spin-wave storage by transferring the collective optical excitations into collective spin excitations. Proof of principle spin-wave quantum memories have been reported in rare-earth doped crystals, using weak coherent states as input [1,2]. Here, I will present our recent results on the realization of multimode spin-wave quantum memories in a Praseodymium doped crystal, using non-classical input light. [1] M. Gündoğan, P. M. Ledingham, K. Kutluer, M. Mazzera and H. de Riedmatten , A solid state spin-wave quantum memory for time-bin qubits, Phys. Rev. Lett. 114, 230501 (2015) [2] P. Jobez, C. Laplane, N. Timoney, N. Gisin, A. Ferrier, P. Goldner, and M. Afzelius, Coherent Spin Control at the Quantum Level in an Ensemble-Based Optical Memory, Phys. Rev. Lett. 114, 230502 (2015)

•Apr 28, 2017•0 citations

Solid State Spin-Wave Quantum Memory for Time-Bin Qubits

Mustafa Gündoğan, Patrick M. Ledingham, Kutlu Kutluer +2 more

We demonstrate the first solid-state spin-wave optical quantum memory with on-demand read-out. Using the full atomic frequency comb scheme in a ${\mathrm{Pr}}^{3+}\ensuremath{\mathbin:}{\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}$ crystal, we store weak coherent pulses at the single-photon level with a signal-to-noise ratio $>10$. Narrow-band spectral filtering based on spectral hole burning in a second ${\mathrm{Pr}}^{3+}\ensuremath{\mathbin:}{\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}$ crystal is used to filter out the excess noise created by control pulses to reach an unconditional noise level of $(2.0\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ photons per pulse. We also report spin-wave storage of photonic time-bin qubits with conditional fidelities higher than achievable by a measure and prepare strategy, demonstrating that the spin-wave memory operates in the quantum regime. This makes our device the first demonstration of a quantum memory for time-bin qubits, with on-demand read-out of the stored quantum information. These results represent an important step for the use of solid-state quantum memories in scalable quantum networks.

arXiv:1501.03980•Physical Review Letters•Jun 12, 2015•213 citations

Storage of photonic time-bin qubits for up to 20 ms in a rare-earth doped crystal

Antonio Ortu, Adrian Holzäpfel, Jean Etesse +1 more

Abstract Long-duration quantum memories for photonic qubits are essential components for achieving long-distance quantum networks and repeaters. The mapping of optical states onto coherent spin-waves in rare earth ensembles is a particularly promising approach to quantum storage. However, it remains challenging to achieve long-duration storage at the quantum level due to read-out noise caused by the required spin-wave manipulation. In this work, we apply dynamical decoupling techniques and a small magnetic field to achieve the storage of six temporal modes for 20, 50, and 100 ms in a 151Eu3+:Y2SiO5 crystal, based on an atomic frequency comb memory, where each temporal mode contains around one photon on average. The quantum coherence of the memory is verified by storing two time-bin qubits for 20 ms, with an average memory output fidelity of F = (85 ± 2)% for an average number of photons per qubit of μin = 0.92 ± 0.04. The qubit analysis is done at the read-out of the memory, using a type of composite adiabatic read-out pulse we developed.

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Single-photon-level optical storage in a solid-state spin-wave memory

Nuala Timoney, Imam Usmani, Pierre Jobez +2 more

A long-lived quantum memory is a firm requirement for implementing a quantum repeater scheme. Recent progress in solid-state rare-earth-ion-doped systems justifies their status as very strong candidates for such systems. Nonetheless an optical memory based on spin-wave storage at the single-photon level has not been shown in such a system to date, which is crucial for achieving the long storage times required for quantum repeaters. In this paper we show that it is possible to execute a complete atomic frequency comb (AFC) scheme, including spin-wave storage, with weak coherent pulses of $\overline{n}=2.5\ifmmode\pm\else\textpm\fi{}0.6$ photons per pulse. We discuss in detail the experimental steps required to obtain this result and demonstrate the coherence of a stored time-bin pulse. We show a noise level of $(7.1\ifmmode\pm\else\textpm\fi{}2.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ photons per mode during storage, and this relatively low noise level paves the way for future quantum optics experiments using spin waves in rare-earth-doped crystals.

arXiv:1301.6924•Physical Review A•Aug 20, 2013•72 citations

High-bandwidth quantum memory protocol for storing single photons in rare-earth doped crystals

Valentina Caprara Vivoli, Nicolas Sangouard, Mikael Afzelius +1 more

We present a detailed analysis of a high-bandwidth quantum memory protocol for storing single photons in a rare-earth-ion doped crystal. The basic idea is to benefit from a coherent free-induced decay type re-emission which occurs naturally when a photon with a broadband spectrum is absorbed by a narrow atomic transition in an optically dense ensemble. This allows for a high-bandwidth memory for realistic material parameters. Long storage time and on-demand readout are obtained by means of spin states in a lambda-type configuration, through the transfer of the optical coherence to a spin coherence (so-called spin-wave storage). We give explicit formulae and show numerical results which make it possible to gain insight into the dependence of the memory efficiency on the optical depth and on the width and the shape of stored photons. We present a feasibility study in rare-earth doped crystals and show that high efficiencies and high bandwidth can be obtained with realistic parameters. High-bandwidth memories using spin-wave storage offers the possibility of very high time-bandwidth products, which is important for experiments where high repetition rates are needed.

arXiv:1305.1863•New Journal of Physics•Sep 25, 2013•24 citations

Realization of Reliable Solid-State Quantum Memory for Photonic Polarization Qubit

Zong‐Quan Zhou, Weibin Lin, Ming Yang +2 more

Faithfully storing an unknown quantum light state is essential to advanced quantum communication and distributed quantum computation applications. The required quantum memory must have high fidelity to improve the performance of a quantum network. Here we report the reversible transfer of photonic polarization states into collective atomic excitation in a compact solid-state device. The quantum memory is based on an atomic frequency comb (AFC) in rare-earth ion-doped crystals. We obtain up to 0.999 process fidelity for the storage and retrieval process of single-photon-level coherent pulse. This reliable quantum memory is a crucial step toward quantum networks based on solid-state devices.

arXiv:1201.4441•Physical Review Letters•May 10, 2012•156 citations
Rare-earth (RE) doped crystals are promising candidates as quantum memories as they offer coherence properties comparable to those of atomic systems, but free of the drawbacks deriving from the atomic motion. The research on RE doped crystals quantum memories has been so far mostly focused on the mapping of quantum bits to optical collective excitations using the atomic frequency comb (AFC) or the gradient echo memory protocols [1-3]. However, this leads to short lived and mostly pre-determined storage. In this contribution, we report the first solid state spin-wave optical quantum memory with on-demand read-out. We also demonstrate the first spin-wave storage of time-bin qubits with conditional fidelities higher than for classical memories [4].
Photonic quantum memories are important devices in quantum information science, and are crucial for several applications including quantum repeaters and quantum networks. Rare-earth (RE) doped crystals are promising candidates as quantum memories for light as they offer coherence properties comparable to those of atomic systems, but free of the drawbacks deriving from atomic motion. The research on RE based quantum memories has been so far mostly focused on the mapping of photonic quantum bits to optical collective excitations, but this leads to short lived and mostly pre-determined storage. However, some RE ions, as Praseodymium and Europium, exhibit the suitable energy level scheme, with three long-lived hyperfine ground states, to enable the spin-wave storage by transferring the collective optical excitations into collective spin excitations. Proof of principle spin-wave quantum memories have been reported in rare-earth doped crystals, using weak coherent states as input [1,2]. Here, I will present our recent results on the realization of multimode spin-wave quantum memories in a Praseodymium doped crystal, using non-classical input light. [1] M. Gündoğan, P. M. Ledingham, K. Kutluer, M. Mazzera and H. de Riedmatten , A solid state spin-wave quantum memory for time-bin qubits, Phys. Rev. Lett. 114, 230501 (2015) [2] P. Jobez, C. Laplane, N. Timoney, N. Gisin, A. Ferrier, P. Goldner, and M. Afzelius, Coherent Spin Control at the Quantum Level in an Ensemble-Based Optical Memory, Phys. Rev. Lett. 114, 230502 (2015)
We demonstrate the first solid-state spin-wave optical quantum memory with on-demand read-out. Using the full atomic frequency comb scheme in a ${\mathrm{Pr}}^{3+}\ensuremath{\mathbin:}{\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}$ crystal, we store weak coherent pulses at the single-photon level with a signal-to-noise ratio >10>10>10. Narrow-band spectral filtering based on spectral hole burning in a second ${\mathrm{Pr}}^{3+}\ensuremath{\mathbin:}{\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}$ crystal is used to filter out the excess noise created by control pulses to reach an unconditional noise level of $(2.0\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ photons per pulse. We also report spin-wave storage of photonic time-bin qubits with conditional fidelities higher than achievable by a measure and prepare strategy, demonstrating that the spin-wave memory operates in the quantum regime. This makes our device the first demonstration of a quantum memory for time-bin qubits, with on-demand read-out of the stored quantum information. These results represent an important step for the use of solid-state quantum memories in scalable quantum networks.
Abstract Long-duration quantum memories for photonic qubits are essential components for achieving long-distance quantum networks and repeaters. The mapping of optical states onto coherent spin-waves in rare earth ensembles is a particularly promising approach to quantum storage. However, it remains challenging to achieve long-duration storage at the quantum level due to read-out noise caused by the required spin-wave manipulation. In this work, we apply dynamical decoupling techniques and a small magnetic field to achieve the storage of six temporal modes for 20, 50, and 100 ms in a 151Eu3+:Y2SiO5 crystal, based on an atomic frequency comb memory, where each temporal mode contains around one photon on average. The quantum coherence of the memory is verified by storing two time-bin qubits for 20 ms, with an average memory output fidelity of F = (85 ± 2)% for an average number of photons per qubit of μin = 0.92 ± 0.04. The qubit analysis is done at the read-out of the memory, using a type of composite adiabatic read-out pulse we developed.
A long-lived quantum memory is a firm requirement for implementing a quantum repeater scheme. Recent progress in solid-state rare-earth-ion-doped systems justifies their status as very strong candidates for such systems. Nonetheless an optical memory based on spin-wave storage at the single-photon level has not been shown in such a system to date, which is crucial for achieving the long storage times required for quantum repeaters. In this paper we show that it is possible to execute a complete atomic frequency comb (AFC) scheme, including spin-wave storage, with weak coherent pulses of $\overline{n}=2.5\ifmmode\pm\else\textpm\fi{}0.6$ photons per pulse. We discuss in detail the experimental steps required to obtain this result and demonstrate the coherence of a stored time-bin pulse. We show a noise level of $(7.1\ifmmode\pm\else\textpm\fi{}2.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ photons per mode during storage, and this relatively low noise level paves the way for future quantum optics experiments using spin waves in rare-earth-doped crystals.
We present a detailed analysis of a high-bandwidth quantum memory protocol for storing single photons in a rare-earth-ion doped crystal. The basic idea is to benefit from a coherent free-induced decay type re-emission which occurs naturally when a photon with a broadband spectrum is absorbed by a narrow atomic transition in an optically dense ensemble. This allows for a high-bandwidth memory for realistic material parameters. Long storage time and on-demand readout are obtained by means of spin states in a lambda-type configuration, through the transfer of the optical coherence to a spin coherence (so-called spin-wave storage). We give explicit formulae and show numerical results which make it possible to gain insight into the dependence of the memory efficiency on the optical depth and on the width and the shape of stored photons. We present a feasibility study in rare-earth doped crystals and show that high efficiencies and high bandwidth can be obtained with realistic parameters. High-bandwidth memories using spin-wave storage offers the possibility of very high time-bandwidth products, which is important for experiments where high repetition rates are needed.
Faithfully storing an unknown quantum light state is essential to advanced quantum communication and distributed quantum computation applications. The required quantum memory must have high fidelity to improve the performance of a quantum network. Here we report the reversible transfer of photonic polarization states into collective atomic excitation in a compact solid-state device. The quantum memory is based on an atomic frequency comb (AFC) in rare-earth ion-doped crystals. We obtain up to 0.999 process fidelity for the storage and retrieval process of single-photon-level coherent pulse. This reliable quantum memory is a crucial step toward quantum networks based on solid-state devices.