Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Quantum 2.0 Conference and Exhibition

Entangling Quantum Memories at High Rate using Gottesman-Kitaev-Preskill Qudits

Prajit Dhara, Liang Jiang, Saikat Guha

Published Jan 1, 2024• 0 citations
Publisher

Abstract

We propose an interface between solid-state quantum memories and Gottesman-Kitaev-Preskill encoded photonic qubits using cavity-assisted controlled phase gates [1, 2]. Our protocol yields capacity-approaching high rate of heralded entanglement among quantum memory registers in the low-loss regime.
DOI
10.1364/quantum.2024.qth3a.20

Related papers

Entangling quantum memories at channel capacity

Prajit Dhara, Liang Jiang, Saikat Guha

Entangling quantum memories, mediated by optical-frequency or microwave channels, at high rates and fidelities is key for linking qubits across short and long ranges. All well-known protocols encode up to one qubit per optical mode, entangling one pair of memory qubits per transmitted mode over the channel, with probability η, the channel’s transmissivity. The rate is proportional to η ideal Bell states (ebits) per mode. The quantum capacity, C(η)=−log2⁡(1−η) ebits per mode, which ≈1.44η for high loss, thereby making these schemes near rate-optimal. However, C(η)→∞ as η→1, making the known schemes highly rate-suboptimal for shorter ranges. We propose a cavity-assisted memory–photon interface that can be used to entangle matter memories with Gottesman–Kitaev–Preskill (GKP) photonic qudits, which, along with dual-homodyne entanglement swaps that retain analog information, enables entangling memories at capacity-approaching rates at low loss. We benefit from the loss resilience of GKP-encoded states and the ability to encode multiple qubits in one mode. Our memory–photon interface further supports the preparation of needed ancilla GKP qudits. We expect our result to spur research in low-loss, high-cooperativity cavity-coupled qubits with high-efficiency optical coupling and demonstrations of high-rate short-range quantum links.

arXiv:2406.04272•Optica Quantum•Sep 22, 2025•0 citations

Coherent State Assisted Entanglement Generation Between Quantum Memories

Chaohan Cui, Prajit Dhara, Saikat Guha

We propose protocols for entanglement generation between cavity-assisted quantum memories using weak bosonic coherent-states. Our protocols are shown to be near-deterministic in the low-loss regime and surpass the 50% success rate upper-bound for single-photon qubit encodings even with practical non-idealities, enabling an exponential rate scaling speed-up for the generation of multipartite entanglement.

arXiv:2504.20344•Jan 1, 2025•0 citations

Interfacing Gottesman-Kitaev-Preskill qubits to quantum memories

Prajit Dhara, Liang Jiang, Saikat Guha

Gottesman-Kitaev-Preskill (GKP) states have been demonstrated to pose significant advantages when utilized for fault-tolerant all optical continuous-variable quantum computing as well as for quantum communications links for entanglement distribution. However interfacing these systems to long-lived solid-state quantum memories has remained an open problem. Here we propose an interface between quantum memories and GKP qubit states based on a cavity-mediated controlled displacement gate. We characterize the quality of memory-GKP entanglement as a function of cavity parameters suggesting optimal regimes of operation for high-quality state transfer between either qubit states. We further extend this protocol to demonstrate the creation of GKP cluster states by avoiding the requirement of ancillary optical quadrature-squeezed light. Utilizing post-selected entanglement swapping operations for GKP qubits, we demonstrate the utility of our protocol for high-rate entanglement generation between quantum memories. Extensions and derivatives of our proposal could enable a wide variety of applications by utilizing the operational trade-offs for qubits encoded in memory and in the GKP basis.

arXiv:2406.04275•Physical Review A•May 28, 2025•4 citations

Remote Gottesman-Kitaev-Preskill Entanglement Generation between Trapped Ions

Haruki Aoki, Kazufumi Tanji, Shohei Kiryu +2 more

Distributing entanglement directly between error-corrected logical qubits is an important capability for scalable quantum networks. We propose a heralded protocol for generating remote entanglement between Gottesman--Kitaev--Preskill qubits encoded in the motional modes of spatially separated trapped ions, using the internal electronic states to interface the motional qubits with emitted photons. We derive the protocol for single-rail and polarization photonic encodings and evaluate the effects of finite GKP squeezing, photon loss, photon recoil, motional heating, and motional dephasing on the decoded logical state. Moreover, we numerically analysed the fidelity of distributed logical Bell-pair fidelity. We find that one can achieve more than 95% of fidelity in the realistic situation. The protocol combines motional-control and photonic-networking operations that have already been demonstrated in trapped-ion experiments.

quant-pharXiv:2610.21754•Oct 16, 2026•0 citations

Quantum repeaters based on stationary and flying Gottesman-Kitaev-Preskill qudits

Stefan Häußler, Peter van Loock

There are various approaches to long-range quantum communication based on conceptually different forms of quantum repeaters. Here, we explore a quantum repeater scheme that employs quantum error correction (QEC) both on the flying (light) qubits and on the stationary (matter) qubits. The idea is to combine the benefits of encoded one-way and two-way schemes where effective channel transmission and loss scaling are enhanced by means of photon loss codes and encoded quantum memories, respectively, while sacrificing some of their advantages, such as high clock rates, independent of classical communication times (one-way), and potentially large segment lengths (two-way). More specifically, we illustrate, propose, and analyze such a quantum repeater using the bosonic Gottesman-Kitaev-Preskill (GKP) code, which naturally enables encoding and QEC of qudits, protecting them against transmission and memory loss, the latter, for instance, occurring on collective spin modes of atomic ensembles. While the encoded one-way and two-way schemes on their own either require very high repeater link coupling efficiencies and GKP squeezing or allow for experimentally more feasible, small values of these parameters, respectively, we find that there are intermediate parameter regimes where the combined repeater protocol is superior.

arXiv:2508.00530•Physical Review Research•Jun 12, 2026•0 citations

Multiplexed Spin Photon Interfaces in Solid State Quantum Memories

Hugues de Riedmatten

We report experiments demonstrating entanglement between a single photon and a multimode solid-state spin wave quantum memory with on demand read-out. We also demonstrate a frequency multiplexed integrated quantum storage device.

Quantum Information and Measurement (QIM)•Jan 1, 2019•0 citations
Entangling quantum memories, mediated by optical-frequency or microwave channels, at high rates and fidelities is key for linking qubits across short and long ranges. All well-known protocols encode up to one qubit per optical mode, entangling one pair of memory qubits per transmitted mode over the channel, with probability η, the channel’s transmissivity. The rate is proportional to η ideal Bell states (ebits) per mode. The quantum capacity, C(η)=−log2⁡(1−η) ebits per mode, which ≈1.44η for high loss, thereby making these schemes near rate-optimal. However, C(η)→∞ as η→1, making the known schemes highly rate-suboptimal for shorter ranges. We propose a cavity-assisted memory–photon interface that can be used to entangle matter memories with Gottesman–Kitaev–Preskill (GKP) photonic qudits, which, along with dual-homodyne entanglement swaps that retain analog information, enables entangling memories at capacity-approaching rates at low loss. We benefit from the loss resilience of GKP-encoded states and the ability to encode multiple qubits in one mode. Our memory–photon interface further supports the preparation of needed ancilla GKP qudits. We expect our result to spur research in low-loss, high-cooperativity cavity-coupled qubits with high-efficiency optical coupling and demonstrations of high-rate short-range quantum links.
Gottesman-Kitaev-Preskill (GKP) states have been demonstrated to pose significant advantages when utilized for fault-tolerant all optical continuous-variable quantum computing as well as for quantum communications links for entanglement distribution. However interfacing these systems to long-lived solid-state quantum memories has remained an open problem. Here we propose an interface between quantum memories and GKP qubit states based on a cavity-mediated controlled displacement gate. We characterize the quality of memory-GKP entanglement as a function of cavity parameters suggesting optimal regimes of operation for high-quality state transfer between either qubit states. We further extend this protocol to demonstrate the creation of GKP cluster states by avoiding the requirement of ancillary optical quadrature-squeezed light. Utilizing post-selected entanglement swapping operations for GKP qubits, we demonstrate the utility of our protocol for high-rate entanglement generation between quantum memories. Extensions and derivatives of our proposal could enable a wide variety of applications by utilizing the operational trade-offs for qubits encoded in memory and in the GKP basis.
Distributing entanglement directly between error-corrected logical qubits is an important capability for scalable quantum networks. We propose a heralded protocol for generating remote entanglement between Gottesman--Kitaev--Preskill qubits encoded in the motional modes of spatially separated trapped ions, using the internal electronic states to interface the motional qubits with emitted photons. We derive the protocol for single-rail and polarization photonic encodings and evaluate the effects of finite GKP squeezing, photon loss, photon recoil, motional heating, and motional dephasing on the decoded logical state. Moreover, we numerically analysed the fidelity of distributed logical Bell-pair fidelity. We find that one can achieve more than 95% of fidelity in the realistic situation. The protocol combines motional-control and photonic-networking operations that have already been demonstrated in trapped-ion experiments.
There are various approaches to long-range quantum communication based on conceptually different forms of quantum repeaters. Here, we explore a quantum repeater scheme that employs quantum error correction (QEC) both on the flying (light) qubits and on the stationary (matter) qubits. The idea is to combine the benefits of encoded one-way and two-way schemes where effective channel transmission and loss scaling are enhanced by means of photon loss codes and encoded quantum memories, respectively, while sacrificing some of their advantages, such as high clock rates, independent of classical communication times (one-way), and potentially large segment lengths (two-way). More specifically, we illustrate, propose, and analyze such a quantum repeater using the bosonic Gottesman-Kitaev-Preskill (GKP) code, which naturally enables encoding and QEC of qudits, protecting them against transmission and memory loss, the latter, for instance, occurring on collective spin modes of atomic ensembles. While the encoded one-way and two-way schemes on their own either require very high repeater link coupling efficiencies and GKP squeezing or allow for experimentally more feasible, small values of these parameters, respectively, we find that there are intermediate parameter regimes where the combined repeater protocol is superior.