dorsal/arxiv
View SchemaInequivalence of pure state ensembles for open quantum systems: the preferred ensembles are those that are physically realizable
| Authors | H. M. Wiseman, John A. Vaccaro |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0112115 |
| URL | https://arxiv.org/abs/quant-ph/0112115 |
| DOI | 10.1103/PhysRevLett.87.240402 |
| Journal | Phys. Rev. Lett 87, 240402 (2001) |
Abstract
An open quantum system in steady state $\hat\rho_{ss}$ can be represented by a weighted ensemble of pure states $\hat\rho_{ss}=\sum_{k}\wp_{k}\ket{\psi_k} \bra{\psi_k}$ in infinitely many ways. A physically realizable (PR) ensemble is one for which some continuous measurement of the environment will collapse the system into a pure state $\ket{\psi(t)}$, stochastically evolving such that the proportion of time for which $\ket{\psi(t)} = \ket{\psi_{k}}$ equals $\wp_{k}$. Some, but not all, ensembles are PR. This constitutes the preferred ensemble fact, with the PR ensembles being the preferred ensembles. We present the necessary and sufficient conditions for a given ensemble to be PR, and illustrate the method by showing that the coherent state ensemble is not PR for an atom laser.
{
"annotation_id": "967de997-dfe0-48b5-802f-3de9af6c6302",
"date_created": "2026-03-02T18:01:48.342000Z",
"date_modified": "2026-03-02T18:01:48.342000Z",
"file_hash": "39f5341759ee814c8c71c4e1bd5e606ee8f4dbe88501219f835efd8f34455bcc",
"private": false,
"record": {
"abstract": "An open quantum system in steady state $\\hat\\rho_{ss}$ can be represented by\na weighted ensemble of pure states $\\hat\\rho_{ss}=\\sum_{k}\\wp_{k}\\ket{\\psi_k}\n\\bra{\\psi_k}$ in infinitely many ways. A physically realizable (PR) ensemble is\none for which some continuous measurement of the environment will collapse the\nsystem into a pure state $\\ket{\\psi(t)}$, stochastically evolving such that the\nproportion of time for which $\\ket{\\psi(t)} = \\ket{\\psi_{k}}$ equals $\\wp_{k}$.\nSome, but not all, ensembles are PR. This constitutes the preferred ensemble\nfact, with the PR ensembles being the preferred ensembles. We present the\nnecessary and sufficient conditions for a given ensemble to be PR, and\nillustrate the method by showing that the coherent state ensemble is not PR for\nan atom laser.",
"arxiv_id": "quant-ph/0112115",
"authors": [
"H. M. Wiseman",
"John A. Vaccaro"
],
"categories": [
"quant-ph"
],
"doi": "10.1103/PhysRevLett.87.240402",
"journal_ref": "Phys. Rev. Lett 87, 240402 (2001)",
"title": "Inequivalence of pure state ensembles for open quantum systems: the preferred ensembles are those that are physically realizable",
"url": "https://arxiv.org/abs/quant-ph/0112115"
},
"schema_id": "dorsal/arxiv",
"source": {
"execution_id": "0cfe8f91-6b8b-4722-a3b6-0b27e007de64",
"id": "arXiv Dataset IDs",
"type": "Model",
"variant": "snapshot-2026-03-01",
"version": "0.1.0"
},
"user_id": 1000002
}