dorsal/arxiv
View SchemaDynamics of Josephson-junction qubits with exactly solvable time-dependent bias pulses
| Authors | V. V. Shamshutdinova, A. S. Kiyko, S. N. Shevchenko, B. F. Samsonov, A. N. Omelyanchouk |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0612195 |
| URL | https://arxiv.org/abs/quant-ph/0612195 |
| Journal | Russ. Phys. J. 51 (2008) 578-586 |
| License | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
Abstract
The quantum dynamics of a two-state system (qubit) can be governed by means of external control parameters present in time-dependent bias pulses of special forms. We consider the class of biases for which the time evolution equation without a dissipation can be solved exactly. Concentrating for definiteness on the flux qubit we calculate the probability of the definite direction of the current in the loop and its time-averaged values as functions of the qubit's control parameters both analytically and solving numerically the equation of motion for the density matrix in the presence of relaxation and decoherence. It is shown that there exist such time-dependent biases that the definite current direction probability with no dissipation taken into account becomes a monotonously growing function of time tending to a value which may exceed 1/2. We also calculate the probability to find the system in the excited state and show the possibility of the inverse population in a properly driven two-state system provided the relaxation and dephasing rates are small enough.
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"abstract": "The quantum dynamics of a two-state system (qubit) can be governed by means\nof external control parameters present in time-dependent bias pulses of special\nforms. We consider the class of biases for which the time evolution equation\nwithout a dissipation can be solved exactly. Concentrating for definiteness on\nthe flux qubit we calculate the probability of the definite direction of the\ncurrent in the loop and its time-averaged values as functions of the qubit\u0027s\ncontrol parameters both analytically and solving numerically the equation of\nmotion for the density matrix in the presence of relaxation and decoherence. It\nis shown that there exist such time-dependent biases that the definite current\ndirection probability with no dissipation taken into account becomes a\nmonotonously growing function of time tending to a value which may exceed 1/2.\nWe also calculate the probability to find the system in the excited state and\nshow the possibility of the inverse population in a properly driven two-state\nsystem provided the relaxation and dephasing rates are small enough.",
"arxiv_id": "quant-ph/0612195",
"authors": [
"V. V. Shamshutdinova",
"A. S. Kiyko",
"S. N. Shevchenko",
"B. F. Samsonov",
"A. N. Omelyanchouk"
],
"categories": [
"quant-ph",
"cond-mat.supr-con"
],
"journal_ref": "Russ. Phys. J. 51 (2008) 578-586",
"license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
"title": "Dynamics of Josephson-junction qubits with exactly solvable time-dependent bias pulses",
"url": "https://arxiv.org/abs/quant-ph/0612195"
},
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