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arXiv 1906.12296quant-ph
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波导QED中的无损光子计数

Nondestructive photon counting in waveguide QED

Daniel Malz, J. Ignacio Cirac

备注：
12+10 pages. Very close to published version. Fourth version includes full level scheme for 87Rb
发表信息：
Phys. Rev. Research 2, 033091 (2020)
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摘要：

数字分辨单光子探测器代表了许多量子光学协议的关键技术，但尽管付出了巨大的努力，最先进的设备仍限于少数光子。相比之下，阵列中的状态相关原子计数可以以极高的保真度高达数百个原子。我们证明了在波导QED中，光子计数的问题可以归结为原子计数，通过纠缠光子态与原子阵列在集体数基。这是可能的，因为入射光子耦合到集体原子状态，并且可以通过将受激原子的第二衰变通道工程化为亚稳态来实现。我们的计划是强大的无序和有限的Purcell因素，其保真度增加的原子数。通过分析再发射光子的态，进一步证明了如果原子的初始态是对称的Dicke态，则可以利用耗散工程实现入射态散射到波导中的光子数的无损测量。我们的结果推广到相关的平台，包括超导量子比特。

英文摘要：

Number-resolving single-photon detectors represent a key technology for a host of quantum optics protocols, but despite significant efforts, state-of-the-art devices are limited to few photons. In contrast, state-dependent atom counting in arrays can be done with extremely high fidelity up to hundreds of atoms. We show that in waveguide QED, the problem of photon counting can be reduced to atom counting, by entangling the photonic state with an atomic array in the collective number basis. This is possible as the incoming photons couple to collective atomic states and can be achieved by engineering a second decay channel of an excited atom to a metastable state. Our scheme is robust to disorder and finite Purcell factors, and its fidelity increases with atom number. Analyzing the state of the re-emitted photons, we further show that if the initial atomic state is a symmetric Dicke state, dissipation engineering can be used to implement a nondestructive photon-number measurement, in which the incident state is scattered into the waveguide unchanged. Our results generalize to related platforms, including superconducting qubits.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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