Quantum Bit Regeneration

Abstract

Decoherence and loss will limit the practicality of quantum cryptography and computing unless successful error correction techniques are developed. To this end, we have discovered a new scheme for perfectly detecting and rejecting the error caused by loss (amplitude damping to a reservoir at T=0), based on using a dual-rail representation of a quantum bit. This is possible because (1) balanced loss does not perform a ``which-path'' measurement in an interferometer, and (2) balanced quantum nondemolition measurement of the ``total'' photon number can be used to detect loss-induced quantum jumps without disturbing the quantum coherence essential to the quantum bit. Our results are immediately applicable to optical quantum computers using single photonics devices.

4 pages, postscript only, figures available at http://feynman.stanford.edu/qcomp

References in corpus (2)

• Measurement of conditional phase shifts for quantum logic
• A Simple Quantum Computer

Cited by in corpus (36)

• Mixed State Entanglement and Quantum Error Correction
• Preserving coherence in quantum computation by pairing quantum bits
• Optical Simulation of Quantum Logic
• Conclusive and arbitrarily perfect quantum state transfer using parallel spin chain channels
• Approximate quantum error correction can lead to better codes
• Single-photon quantum nondemolition detectors constructed with linear optics and projective measurements
• A quantum Fredkin gate
• Quantum Gates and Circuits
• Equivalence between an optomechanical system and a Kerr medium
• Optimum unambiguous discrimination among linearly-independent non-orthogonal quantum states and its optical realization
• Realization of near-deterministic arithmetic operations and quantum state engineering
• Quantum gates on hybrid qudits
• Prevention of dissipation with two particles
• Optimal quantum codes for preventing collective amplitude damping
• Remote preparation of arbitrary time-encoded single-photon ebits
• One-step implementation of a hybrid Fredkin gate with quantum memories and single superconducting qubit in circuit QED and its applications
• Quantum error correction may delay, but also cause, entanglement sudden death
• Generalized Quantum Search with Parallelism
• Multiparticle Entanglement in the Lipkin-Meshkov-Glick Model
• Decoherence, Control, and Symmetry in Quantum Computers
• Perturbative expansions for the fidelities and spatially correlated dissipation of quantum bits
• Quantum Computation and Spin Physics
• Unselective ground-state blockade of Rydberg atoms for implementing quantum gates
• Quantum Gambling Using Two Nonorthogonal States
• Efficient Schemes for Reducing Imperfect Collective Decoherences
• Simple implementation of high fidelity controlled-$i$SWAP gates and quantum circuit exponentiation of non-Hermitian gates
• Photon-photon gates in Bose-Einstein condensates
• One-way quantum computing in a decoherence-free subspace
• Error-correcting one-way quantum computation with global entangling gates
• Conditional sign flip via teleportation
• Effects of Loss and Decoherence on a Simple Quantum Computer
• Letting the tiger out of its cage: bosonic coding without concatenation
• Universal quantum computation using atoms in cross-cavity systems
• Recovering Coherence via Conditional Measurements
• On interchanging the states of a pair of qudits
• Creating Boolean Functions for the Five-EPR-Pair, Single-Error-Correcting Code