Abstract
Quantum networks can enable various applications such as distributed quantum computing, long-distance quantum communication, and network-based quantum sensing with unprecedented performances. One of the most important building blocks for a quantum network is a photonic quantum memory which serves as the interface between the communication channel and the local functional unit. A programmable quantum memory which can process a large stream of flying qubits and fulfill the requirements of multiple core functions in a quantum network is still to be realized. Here we report a high-performance quantum memory which can simultaneously store 72 optical qubits carried by 144 spatially separated atomic ensembles and support up to a thousand consecutive write or read operations in a random access way, 2 orders of magnitude larger than the previous record. Because of the built-in programmability, this quantum memory can be adapted on demand for several functions. As example applications, we realize quantum queue, stack, and buffer which closely resemble the counterpart devices for classical information processing. We further demonstrate the storage and reshuffle of four entangled pairs of photonic pulses with probabilistic arrival time and arbitrary release order via the memory, which is an essential requirement for the realization of quantum repeaters and efficient routing in quantum networks. Realization of this multipurpose programmable quantum memory thus constitutes a key enabling building block for future large-scale fully functional quantum networks.
- Received 5 December 2023
- Accepted 27 February 2024
DOI:https://doi.org/10.1103/PhysRevX.14.021018
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Like the current global Internet, a future quantum Internet could link devices via optical channels and open wide opportunities for numerous applications. However, because quantum information is fragile and difficult to manipulate, the core device in a quantum network—the optical quantum memory—must be very robust. To build a large-scale and complex quantum network, the optical quantum memory must be able to handle many optical qubits in a random-access way, as in traditional computing, and be adapted for various applications on demand, which have not yet been implemented. Here, we implement a fully programmable quantum memory to manipulate a large stream of optical qubits and support key applications in multiple scenarios.
Our multipurpose quantum memory is based on a neutral atomic cloud and 2D addressing units. With the help of both long storage time and short access time, we can simultaneously store 72 optical quantum bits in the memory and perform 1000 write-or-read operations to the optical stream in an arbitrarily programmable style. In addition, we adapt this versatile memory to demonstrate quantum queue, stack, and buffer—the quantum counterparts of widely used data devices in classical information science—as well as the storage and reshuffle of four randomly generated entangled photon pairs, which is important for the implementation of a quantum repeater.
By further improving the efficiency and storage time, as well as equipping it with a wavelength conversion device, we expect this multipurpose quantum memory will be a key component for photonic quantum information processing and large-scale quantum networks.
