EXPLORING A NEW POST-SELECTION CONDITION FOR EFFICIENT LINEAR OPTICS COMPUTATION

2005 ◽  
Vol 03 (04) ◽  
pp. 611-621
Author(s):  
RUBEN COEN CAGLI ◽  
PAOLO ANIELLO ◽  
NICOLA CESARIO ◽  
FRANCESCO FONCELLINO
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Upper Bound ◽  
Quantum Information Processing ◽  
Single Photon ◽  
Success Probability ◽  
Rigorous Proof ◽  
Linear Optics ◽  
Selection Condition ◽  
The One

Recently, it has been shown that fundamental gates for theoretically efficient quantum information processing can be realized by using single photon sources, linear optics and photon counters. One of these fundamental gates is the NS-gate, that is, the one-mode non-linear sign shift. In this work, firstly, we prove by an elementary and rigorous proof that the upper bound of success probability of NS-gates with only one helper photon and an undefined number of ancillary modes is bounded by 0.25. Secondly, we explore the upper bound of the success probability of the NS-gate with a new post-selection measurement. The idea behind this new post-selection measurement is to condition the success of NS-gate transformation to the observation of only one helper photon in whichever of the output modes.

scholarly journals Optical Chirality and Single-Photon Isolation

2020 ◽  
Author(s):  
Lei Tang ◽  
Keyu Xia
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Single Photon ◽  
Kerr Nonlinearity ◽  
Single Photons ◽  
Optical Isolation ◽  
Optical Chirality ◽  
Magneto Optical Effect ◽  
Quantum Optical

Optical isolation is important for protecting a laser from damage due to the detrimental back reflection of light. It typically relies on breaking Lorentz reciprocity and normally is achieved via the Faraday magneto-optical effect, requiring a strong external magnetic field. Single-photon isolation, the quantum counterpart of optical isolation, is the key functional component in quantum information processing, but its realization is challenging. In this chapter, we present all-optical schemes for isolating the backscattering from single photons. In the first scheme, we show the single-photon isolation can be realized by using a chiral quantum optical system, in which a quantum emitter asymmetrically couples to nanowaveguide modes or whispering-gallery modes with high optical chirality. Secondly, we propose a chiral optical Kerr nonlinearity to bypass the so-called dynamical reciprocity in nonlinear optics and then achieve room-temperature photon isolation with low insertion loss. The concepts we present may pave the way for quantum information processing in an unconventional way.

scholarly journals DECOHERENCE-FREE QUANTUM MEMORY FOR PHOTONIC STATE USING ATOMIC ENSEMBLES

2009 ◽  
Vol 07 (04) ◽  
pp. 811-820 ◽  
Author(s):  
FENG MEI ◽  
YA-FEI YU ◽  
ZHI-MING ZHANG
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Large Scale ◽  
Quantum Information Processing ◽  
Single Photon ◽  
Quantum Memory ◽  
Single Photon Detection ◽  
Atomic Ensembles ◽  
Optical Elements ◽  
Photonic State

Large scale quantum information processing requires stable and long-lived quantum memories. Here, using atom-photon entanglement, we propose an experimentally feasible scheme to realize decoherence-free quantum memory with atomic ensembles, and show one of its applications, remote transfer of unknown quantum state, based on laser manipulation of atomic ensembles, photonic state operation through optical elements, and single-photon detection with moderate efficiency. The scheme, with inherent fault-tolerance to the practical noise and imperfections, allows one to retrieve the information in the memory for further quantum information processing within the reach of current technology.

Single-photon counters in the telecom wavelength region of 1550 nm for quantum information processing

2001 ◽  
Vol 48 (13) ◽  
pp. 1983-1995 ◽  
Author(s):  
Mohamed Bourennane ◽  
Anders Karlsson ◽  
Juan Pena Ciscar ◽  
Markus Mathés
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Quantum Information Processing ◽  
Single Photon ◽  
Wavelength Region ◽  
Telecom Wavelength

Computational model underlying the one-way quantum computer

2002 ◽  
Vol 2 (6) ◽  
pp. 443-486
Author(s):  
R. Raussendorf ◽  
H. Briegel
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Computational Model ◽  
Quantum Logic ◽  
Quantum Information Processing ◽  
Quantum Computer ◽  
Quantum Circuit ◽  
Single Step ◽  
Clifford Group ◽  
The One

In this paper we present the computational model underlying the one-way quantum computer which we introduced recently [Phys. Rev. Lett. {\bf{86}}, 5188 (2001)]. The one-way quantum computer has the property that any quantum logic network can be simulated on it. Conversely, not all ways of quantum information processing that are possible with the one-way quantum computer can be understood properly in network model terms. We show that the logical depth is, for certain algorithms, lower than has so far been known for networks. For example, every quantum circuit in the Clifford group can be performed on the one-way quantum computer in a single step.

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