Details
| Original language | English |
|---|---|
| Pages (from-to) | 211-232 |
| Number of pages | 22 |
| Journal | J. Mod. Opt. |
| Volume | 47 |
| Issue number | 2-3 |
| Publication status | Published - 2000 |
Abstract
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In: J. Mod. Opt., Vol. 47, No. 2-3, 2000, p. 211-232.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Universal-NOT gate
AU - Buzek, V.
AU - Hillery, M.
AU - Werner, R. F.
N1 - Physics of quantum information
PY - 2000
Y1 - 2000
N2 - It is not a problem to complement a classical bit, i.e. to change the value of a bit, a 0 to a 1 and vice versa. This is accomplished by a NOT gate. Complementing a qubit in an unknown state, however, is another matter. We show that this operation cannot be done perfectly. We define the Universal-NOT (U-NOT) gate which out of N identically prepared pure input qubits generates M output qubits in a state which is as close as possible to the perfect complement. This gate can be realized by classical estimation and subsequent re-preparation of complements of the estimated state. Its fidelity is therefore equal to the fidelity F= (N+1)/(N+2) of optimal estimation, and does not depend on the required number of outputs. We also show that when some additional a priori information about the state of input qubit is available, than the fidelity of the quantum NOT gate can be much better than the fidelity of estimation.
AB - It is not a problem to complement a classical bit, i.e. to change the value of a bit, a 0 to a 1 and vice versa. This is accomplished by a NOT gate. Complementing a qubit in an unknown state, however, is another matter. We show that this operation cannot be done perfectly. We define the Universal-NOT (U-NOT) gate which out of N identically prepared pure input qubits generates M output qubits in a state which is as close as possible to the perfect complement. This gate can be realized by classical estimation and subsequent re-preparation of complements of the estimated state. Its fidelity is therefore equal to the fidelity F= (N+1)/(N+2) of optimal estimation, and does not depend on the required number of outputs. We also show that when some additional a priori information about the state of input qubit is available, than the fidelity of the quantum NOT gate can be much better than the fidelity of estimation.
M3 - Article
VL - 47
SP - 211
EP - 232
JO - J. Mod. Opt.
JF - J. Mod. Opt.
IS - 2-3
ER -