173 research outputs found
Concatenated Quantum Codes
One of the main problems for the future of practical quantum computing is to
stabilize the computation against unwanted interactions with the environment
and imperfections in the applied operations. Existing proposals for quantum
memories and quantum channels require gates with asymptotically zero error to
store or transmit an input quantum state for arbitrarily long times or
distances with fixed error. In this report a method is given which has the
property that to store or transmit a qubit with maximum error
requires gates with error at most and storage or channel elements
with error at most , independent of how long we wish to store the
state or how far we wish to transmit it. The method relies on using
concatenated quantum codes with hierarchically implemented recovery operations.
The overhead of the method is polynomial in the time of storage or the distance
of the transmission. Rigorous and heuristic lower bounds for the constant
are given.Comment: 16 pages in PostScirpt, the paper is also avalaible at
http://qso.lanl.gov/qc
- …