Optical coherence and teleportation: why a laser is a clock and not a quantum channel

Howard M. Wiseman

doi:10.1117/12.497090

16 May 2003 Optical coherence and teleportation: why a laser is a clock, and not a quantum channel

Howard M. Wiseman

Proceedings Volume 5111, Fluctuations and Noise in Photonics and Quantum Optics; (2003) https://doi.org/10.1117/12.497090
Event: SPIE's First International Symposium on Fluctuations and Noise, 2003, Santa Fe, New Mexico, United States

Abstract

It has been argued that continuous-variable quantum teleportation at optical frequencies has not been achieved because the source used was not 'truly coherent'. While arguing against Rudolph and Sanders, also accept that an 'absolute phase' is achievable, even if it has not been achieved yet. I will argue to the contrary that 'true coherence' or 'absolute phase' is always illusory, as the concept of absolute time on a scale beyond direct human experience is meaningless. All we can ever do is to use an agreed time standard. in this context, laser beam is fundamentally as good a 'clock' as any other. I explain in detail why this claim is true, and defend my argument against various objections. In the process I discuss super-selection rules, quantum work by myself and Berry and myself to show that a Heisenberg-limited laser with a mean photon number μ can synchronize M independent clocks each with a mean-square error of square root M/4μ radians².

Citation Download Citation

Howard M. Wiseman "Optical coherence and teleportation: why a laser is a clock, and not a quantum channel", Proc. SPIE 5111, Fluctuations and Noise in Photonics and Quantum Optics, (16 May 2003); https://doi.org/10.1117/12.497090

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