Quantum Optics and Quantum Information - Quantum Memory
Quantum Memory in Cold Atomic Ensemble
Deterministic and Storable Single-Photons from Cold Atomic ensemble
A
single-photon source is realized with a cold atomic ensemble (Rb 87 atoms).
A single excitation,written in an atomic quantum memory by Raman scattering
of a laser pulse, is retrieved deterministically as a single photon at a
predetermined time. It is shown that the production rate of single photons
can be enhanced considerably by a feedback circuit while the single-photon
quality is conserved. Such a singlephoton source is well suited for future
large-scale realization of quantum communication and linear optical quantum
computation. Details
are in the reference below.
Reference:
Deterministic
and Storable Single-Photon Source Based on a Quantum Memory
Phys. Rev. Lett. 97, 173004 (2006)
Entanglement of independent single photons
We
have created independent, synchronized single-photon sources with built-in
quantum memory based on two remote cold atomic ensembles. The synchronized
single photons are used to demonstrate efficient generation of entanglement.
The resulting entangled photon pairs violate a Bell's inequality by 5 standard
deviations. Our synchronized single photons with their long coherence time
of 25 ns and the efficient creation of entanglement serve as an ideal building
block for scalable linear optical quantum information processing. Details
are in the reference below.
Reference:
Synchronized Independent Narrow-Band Single Photons and Efficient Generation
of Photonic Entanglement
Phys. Rev. Lett. 98, 180503 (2007)
Hong-Ou-Mandel
dip in time and frequency domain respectively
Quantum connection of two remote atomic ensembles: torwards a quantum repeater
We
have demonstrated a novel way to efficiently and very robust create an entanglement
between an atomic and a photonic qubit. A single laser beam is used to excite
one atomic ensemble and two different spatial modes of scattered Raman fields
are collected to generate the atom-photon entanglement. With the help of
build-in quantum memory, the entanglement still exists after 20.5 micro
second storage time which is further proved by the violation of CHSH type
Bell's inequality. Our entanglement procedure is the building block for
a novel robust quantum repeater architecture [Zhao et al, Phys. Rev. Lett.
98, 240502 (2007)]. Our approach can be easily extended to generate high
dimensional atom-photon entanglements. Details are in the reference below.
References:
A Robust Atom-Photon Entanglement Source for Quantum Repeaters, arXiv:0706.2327.
Memory-built-in quantum teleportation with photonic and atomic qubits, arXiv:0705.1256.
Long Lifetime of Spin Wave
We are working on optical dipole trap and operating the atoms at clock state
