Enhancing Multiphoton Rates with Quantum Memories

TLDR

Single photons are a vital resource for optical quantum information processing, but efficient deterministic sources are lacking; current experiments rely on nondeterministic sources with heralding or postselection, resulting in very low data rates even for eight photons, and quantum memories that store photons until needed offer a potential solution to this scaling problem. The authors analyze how quantum memories can dramatically increase multiphoton production rates. They identify the figure of merit ηB, the product of memory efficiency η and time‑bandwidth product B, as the key parameter governing this enhancement.

Abstract

Single photons are a vital resource for optical quantum information processing. Efficient and deterministic single photon sources do not yet exist, however. To date, experimental demonstrations of quantum processing primitives have been implemented using nondeterministic sources combined with heralding and/or postselection. Unfortunately, even for eight photons, the data rates are already so low as to make most experiments impracticable. It is well known that quantum memories, capable of storing photons until they are needed, are a potential solution to this "scaling catastrophe." Here, we analyze in detail the benefits of quantum memories for producing multiphoton states, showing how the production rates can be enhanced by many orders of magnitude. We identify the quantity ηB as the most important figure of merit in this connection, where η and B are the efficiency and time-bandwidth product of the memories, respectively.