dorsal/arxiv
View SchemaAdaptive Phase Measurements in Linear Optical Quantum Computation
| Authors | T. C. Ralph, A. P. Lund, H. M. Wiseman |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0507192 |
| URL | https://arxiv.org/abs/quant-ph/0507192 |
| DOI | 10.1088/1464-4266/7/10/007 |
| Journal | J. Opt. B: Quantum Semiclass. Opt., 7, S245-S249, 2005 |
Abstract
Photon counting induces an effective nonlinear optical phase shift on certain states derived by linear optics from single photons. Although this no nlinearity is nondeterministic, it is sufficient in principle to allow scalable linear optics quantum computation (LOQC). The most obvious way to encode a qubit optically is as a superposition of the vacuum and a single photon in one mode -- so-called "single-rail" logic. Until now this approach was thought to be prohibitively expensive (in resources) compared to "dual-rail" logic where a qubit is stored by a photon across two modes. Here we attack this problem with real-time feedback control, which can realize a quantum-limited phase measurement on a single mode, as has been recently demonstrated experimentally. We show that with this added measurement resource, the resource requirements for single-rail LOQC are not substantially different from those of dual-rail LOQC. In particular, with adaptive phase measurements an arbitrary qubit state $\alpha \ket{0} + \beta\ket{1}$ can be prepared deterministically.
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"abstract": "Photon counting induces an effective nonlinear optical phase shift on certain\nstates derived by linear optics from single photons. Although this no\nnlinearity is nondeterministic, it is sufficient in principle to allow scalable\nlinear optics quantum computation (LOQC). The most obvious way to encode a\nqubit optically is as a superposition of the vacuum and a single photon in one\nmode -- so-called \"single-rail\" logic. Until now this approach was thought to\nbe prohibitively expensive (in resources) compared to \"dual-rail\" logic where a\nqubit is stored by a photon across two modes. Here we attack this problem with\nreal-time feedback control, which can realize a quantum-limited phase\nmeasurement on a single mode, as has been recently demonstrated experimentally.\nWe show that with this added measurement resource, the resource requirements\nfor single-rail LOQC are not substantially different from those of dual-rail\nLOQC. In particular, with adaptive phase measurements an arbitrary qubit state\n$\\alpha \\ket{0} + \\beta\\ket{1}$ can be prepared deterministically.",
"arxiv_id": "quant-ph/0507192",
"authors": [
"T. C. Ralph",
"A. P. Lund",
"H. M. Wiseman"
],
"categories": [
"quant-ph"
],
"doi": "10.1088/1464-4266/7/10/007",
"journal_ref": "J. Opt. B: Quantum Semiclass. Opt., 7, S245-S249, 2005",
"title": "Adaptive Phase Measurements in Linear Optical Quantum Computation",
"url": "https://arxiv.org/abs/quant-ph/0507192"
},
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