|
| related topics |
| {time, wave, function} |
| {state, states, coherent} |
| {level, atom, field} |
| {state, states, entangled} |
| {cavity, atom, atoms} |
| {time, decoherence, evolution} |
| {cos, sin, state} |
| {state, phys, rev} |
| {trap, ion, state} |
| {equation, function, exp} |
| {phase, path, phys} |
| {temperature, thermal, energy} |
| {group, space, representation} |
| {entanglement, phys, rev} |
| {information, entropy, channel} |
| {qubit, qubits, gate} |
|
On the Preparation of Pure States in Resonant Microcavities
Per K. Rekdal, Bo-Sture K. Skagerstam, Peter L. Knight
abstract: We consider the time evolution of the radiation field (R) and a two-level
atom (A) in a resonant microcavity in terms of the Jaynes-Cummings model with
an initial general pure quantum state for the radiation field. It is then
shown, using the Cauchy-Schwarz inequality and also a Poisson resummation
technique, that {\it perfect} coherence of the atom can in general never be
achieved. The atom and the radiation field are, however, to a good
approximation in a pure state $|\psi >_A\otimes|\psi >_R$ in the middle of what
has been traditionally called the ``collapse region'', independent of the
initial state of the atoms, provided that the initial pure state of the
radiation field has a photon number probability distribution which is
sufficiently peaked and phase differences that do not vary significantly around
this peak. An approximative analytic expression for the quantity
$\Tr[\rho^2_{A}(t)]$, where $\rho_{A}(t)$ is the reduced density matrix for the
atom, is derived. We also show that under quite general circumstances an
initial entangled pure state will be disentangled to the pure state $|\psi
>_{A\otimes R}$.
- oai_identifier:
- oai:arXiv.org:quant-ph/0301148
- categories:
- quant-ph
- comments:
- 14 pages and 3 figures
- arxiv_id:
- quant-ph/0301148
- created:
- 2003-01-27
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