Efficient analysis of entangled photons and single photons

The quantum Rayleigh spontaneous emission replaces entangled photons with independent ones in homogeneous dielectric media where single photons cannot propagate in a straight line. Single and independent groups of photons, described by the original bare states of Jaynes-Cummings model, deliver the correct expectation values for the number of photons carried by a photonic wavefront, its complex optical field, and phase quadratures. The intrinsic longitudinal field profile associated with a photonic wavefront is derived for any instantaneous number of photons. These photonic properties enable a step-by-step analysis of various beam splitters and interferometric filters. As a result, generalized expressions are derived for the correlation functions characterizing counting of coincident numbers of photons for fourth-order interference, whether classical or quantum optical, without entangled photons.

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Weak measurement of the arrival times of single photons and pairs of entangled photons

Physical Review A ◽

10.1103/physreva.69.042103 ◽

2004 ◽

Vol 69 (4) ◽

Cited By ~ 16

Author(s):

S. E. Ahnert ◽

M. C. Payne

Keyword(s):

Weak Measurement ◽

Single Photons ◽

Entangled Photons ◽

Arrival Times

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Real-time shaping of entangled photons by classical control and feedback

Science Advances ◽

10.1126/sciadv.abb6298 ◽

2020 ◽

Vol 6 (37) ◽

pp. eabb6298 ◽

Cited By ~ 1

Author(s):

Ohad Lib ◽

Giora Hasson ◽

Yaron Bromberg

Keyword(s):

Real Time ◽

Quantum Correlations ◽

Great Promise ◽

Single Photons ◽

Entangled Photons ◽

Quantum Communications ◽

Recent Developments ◽

Wavefront Shaping ◽

Classical Control ◽

And Control

Quantum technologies hold great promise for revolutionizing photonic applications such as cryptography. Yet, their implementation in real-world scenarios is challenging, mostly because of sensitivity of quantum correlations to scattering. Recent developments in optimizing the shape of single photons introduce new ways to control entangled photons. Nevertheless, shaping single photons in real time remains a challenge due to the weak associated signals, which are too noisy for optimization processes. Here, we overcome this challenge and control scattering of entangled photons by shaping the classical laser beam that stimulates their creation. We discover that because the classical beam and the entangled photons follow the same path, the strong classical signal can be used for optimizing the weak quantum signal. We show that this approach can increase the length of free-space turbulent quantum links by up to two orders of magnitude, opening the door for using wavefront shaping for quantum communications.

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