Hewlett packard development co (us)

Abstract

Nonlinear electromagnetic elements can efficiently implement quantum information processing tasks such as controlled phase shifts, non-demolition state detection, quantum subspace projections, non-demolition Bell state analysis, heralded state preparation, quantum non-demolition encoding, and fundamental quantum gate operations. Direct use of electromagnetic non-linearity can amplify small phase shifts and use feed forward systems in a near deterministic manner with high operating efficiency. Measurements using homodyne detectors can cause near deterministic projection of input states on a Hilbert subspace identified by the measurement results. Feed forward operation can then alter the projected state if desired to achieve a desired output state with near 100% efficiency.

Description

Background technique

[0001] Quantum information processing generally involves manipulating or using quantum states to store or communicate information or to perform computations. Various systems with quantum states have been proposed or used in quantum information processing. For example, optical systems can manipulate quantum states of light to perform specific quantum information processing tasks.

[0002] Quantum computer architectures based on linear optical elements and feed-forward systems with nonlinearities induced by light detection were originally described by E. Knill, R. Laflamme, and G.J. Milburn in "A scheme for efficient quantum computing using linear optical components" ("A Scheme for Efficient Quantum Computation with Linear Optics," Nature 409, 47 (2001)). Although this proposal demonstrates that linear optics quantum computing (LOQC) is possible in principle, scalable systems based on this approach require impractically many quantum resources for reliable ...

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