Remote entanglement via adiabatic passage using a tunably-dissipative quantum communication system

TL;DR

This paper demonstrates a superconducting quantum communication system that uses adiabatic protocols to achieve high-fidelity remote entanglement and state transfer, even with tunable dissipation in the communication channel.

Contribution

It introduces a tunably-dissipative superconducting communication system and shows that adiabatic protocols outperform relay methods under channel loss.

Findings

Achieved 99% quantum state transfer efficiency.

Generated Bell states with 96% fidelity.

Adiabatic protocol outperforms relay method under loss.

Abstract

Effective quantum communication between remote quantum nodes requires high fidelity quantum state transfer and remote entanglement generation. Recent experiments have demonstrated that microwave photons, as well as phonons, can be used to couple superconducting qubits, with a fidelity limited primarily by loss in the communication channel. Adiabatic protocols can overcome channel loss by transferring quantum states without populating the lossy communication channel. Here we present a unique superconducting quantum communication system, comprising two superconducting qubits connected by a 0.73 m-long communication channel. Significantly, we can introduce large tunable loss to the channel, allowing exploration of different entanglement protocols in the presence of dissipation. When set for minimum loss in the channel, we demonstrate an adiabatic quantum state transfer protocol that achieves 99% transfer efficiency as well as the deterministic generation of entangled Bell states with a fidelity of 96%, all without populating the intervening communication channel, and competitive with a qubit-resonant mode-qubit relay method. We also explore the performance of the adiabatic protocol in the presence of significant channel loss, and show that the adiabatic protocol protects against loss in the channel, achieving higher state transfer and entanglement fidelities than the relay method.