Physical Sciences Inc. (PSI) and the University of Illinois Urbana-Champaign (UIUC) will develop integrated optical frequency shifters to enable Quantum-memory Wavelength-Division Multiplexing (QWDM). Our approach will enable the connection of multiple quantum memory registers across a free-space or fiber optical channel, increasing the bandwidth of near-term quantum networks by 10–100×. As most optical quantum memories operate at a single wavelength we cannot readily apply wavelength-division multiplexing (WDM) techniques to increase the bandwidth of a quantum link. To overcome this challenge, we propose to utilize a high-efficiency frequency shifters at the transmitter to shift each quantum register within a memory unit onto a separate wavelength channel that we can combine using standard WDM techniques. After transmitting the multiplexed signal over a free-space or fiber link, a complimentary device at the receiver will de-multiplex the photons and a second set of frequency shifters will shift the wavelengths back to original native frequency of the quantum memory’s register. Within Phase I, we will design and demonstrate a compact on-chip, high-efficiency frequency shifter operating at a native quantum memory wavelength using an approach that can be readily adapted to any existing quantum memory configuration at visible and near-infrared wavelengths. These results, in conjunction with an architecture-design that can efficiently shift and route multiple photons to different registers within a quantum memory, will pave the way for the creation of a highly scalable quantum networks using QWDM.
The development of quantum communications and networks are a key technology to enable secure communication, sensor arrays, and quantum computer networks. Our proposed technology will enable wavelength-division multiplexing techniques to greatly increase the bandwidth of any free-space or fiber link that interfaces quantum memories and heterogeneous single- and entangled-photon sources.
Future quantum networks will require quantum memories (QM) that are linked by photons transmitted over physical channels. As most QMs utilize a fixed optical frequency, QWDM are a general-purpose component to scale bandwidth without introducing additional physical channels. Such frequency conversion methods are applicable to photons from QMs, as well as the sources of the photons themselves.