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Title: Conditional π-Phase Shift of Single-Photon-Level Pulses at Room Temperature
The development of useful photon-photon interactions can trigger numerous breakthroughs in quantum information science, however, this has remained a considerable challenge spanning several decades. Here, we demonstrate the first room-temperature implementation of large phase shifts (≈π) on a single-photon level probe pulse (1.5μs) triggered by a simultaneously propagating few-photon-level signal field. This process is mediated by Rb87 vapor in a double-Λ atomic configuration. We use homodyne tomography to obtain the quadrature statistics of the phase-shifted quantum fields and perform maximum-likelihood estimation to reconstruct their quantum state in the Fock state basis. For the probe field, we have observed input-output fidelities higher than 90% for phase-shifted output states, and high overlap (over 90%) with a theoretically perfect coherent state. Our noise-free, four-wave-mixing-mediated photon-photon interface is a key milestone toward developing quantum logic and nondemolition photon detection using schemes such as coherent photon conversion.  more » « less
Award ID(s):
1707919
PAR ID:
10345689
Author(s) / Creator(s):
Date Published:
Journal Name:
Physical review letters
Volume:
125
ISSN:
1092-0145
Page Range / eLocation ID:
243601
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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