99 research outputs found
Quantum memory for squeezed light
We produce a 600-ns pulse of 1.86-dB squeezed vacuum at 795 nm in an optical
parametric amplifier and store it in a rubidium vapor cell for 1 us using
electromagnetically induced transparency. The recovered pulse, analyzed using
time-domain homodyne tomography, exhibits up to 0.21+-0.04 dB of squeezing. We
identify the factors leading to the degradation of squeezing and investigate
the phase evolution of the atomic coherence during the storage interval.Comment: To appear in PRL. Changes to version 3: we present a larger data set
featuring somewhat less squeezing, but also better statistics and a lower
margin of error. Some additional revisions are made in response to the
referees' comment
Hong-Ou-Mandel interference of polarization qubits stored in independent room-temperature quantum memories
First generation quantum repeater networks require independent quantum
memories capable of storing and retrieving indistinguishable photons to perform
quantum-interference-mediated high-repetition entanglement swapping operations.
The ability to perform these coherent operations at room temperature is of
prime importance in order to realize large scalable quantum networks. Here we
address these significant challenges by observing Hong-Ou-Mandel (HOM)
interference between indistinguishable photons carrying polarization qubits
retrieved from two independent room-temperature quantum memories. Our
elementary quantum network configuration includes: (i) two independent sources
generating polarization-encoded qubits; (ii) two atomic-vapor dual-rail quantum
memories; and (iii) a HOM interference node. We obtained interference
visibilities after quantum memory retrieval of for few-photon level inputs and for single-photon level inputs. Our prototype
network lays the groundwork for future large-scale memory-assisted quantum
cryptography and distributed quantum networks.Comment: 12 pages, 6 figure
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