On-demand Quantum State Transfer and Entanglement between Remote Microwave Cavity Memories
The paper addresses the critical challenge in modular quantum computing architectures to rapidly and efficiently distribute quantum information through propagating signals. This paper demonstrates a noteworthy advancement in quantum communication by achieving deterministic quantum state transfer between remote superconducting cavity memories via traveling microwave photons. The authors report a 76% fidelity in the deterministic transfer of quantum bits, which can be increased to 87% with heralding techniques, accompanied by a success probability of 0.87. Moreover, remote entanglement generation surpasses the photon loss rate in either memory by a factor of three, indicating high robustness.
The protocol deployed for quantum state transfer leverages a parametric conversion-based communication channel. The setup involves identically-constructed circuit QED modules acting as sender and receiver, linked by a transmission line and circulator. These modules host high-Q memory cavities and communication modes. Encoding and conversion processes are facilitated by parametric drives, which induce coupling between memory and communication modes within each module. The reported efficiency of wavepacket release and subsequent absorption stands at 93%, but the overall programmatic transfer efficiency reaches 74% due to additional inefficiency sources including unwanted transmon excitations and imperfect pulse shaping.
An additional experimental achievement is the transference of quantum error correction code words. The authors propose that this lays the groundwork for effectively integrating quantum error correction (QEC) to mitigate photon loss, thereby enhancing the fidelity of data transfer potentially to exceed traditional error thresholds to facilitate scalable quantum networks.
The implications of these findings are substantial for enhancing the connectivity of superconducting quantum devices through modular networks. This work presents a significant step towards the construction of fault-tolerant quantum computers capable of modular expansion. The demonstrated approach paves the pathway for deterministic improvements harnessable with QEC. By maintaining state independence throughout the transfer process, the platform shows readiness to adopt advanced error correction methodologies, specifically tailored to modular network architectures.
Future directions include optimizing the transmon thermalization rates and enhancing parameter engineering to address higher order transition challenges. Additionally, extending this methodology to perform non-local quantum gates and entanglement distillation could yield a broad-based implementation of distributed quantum computation. The presented experimental results hold potential for transformative advancements in superconducting circuit-based quantum computing, and further research along these outlines promises profound impacts on the field of quantum information science.
