scholarly journals Theory of Photon Subtraction for Two-Mode Entangled Light Beams

2021 ◽  
Vol 3 (3) ◽  
pp. 500-516
Author(s):  
Oscar Rosas-Ortiz ◽  
Kevin Zelaya
Keyword(s):  
Beam Splitter ◽  
Input State ◽  
Single Photons ◽  
Nonclassical States ◽  
Theoretical Formulation ◽  
Compact Expression ◽  
Photon Subtraction ◽  
Classical Fields ◽  
Output Field ◽  
Light Beams

Photon subtraction is useful to produce nonclassical states of light addressed to applications in photonic quantum technologies. After a very accelerated development, this technique makes possible obtaining either single photons or optical cats on demand. However, it lacks theoretical formulation enabling precise predictions for the produced fields. Based on the representation generated by the two-mode SU(2) coherent states, we introduce a model of entangled light beams leading to the subtraction of photons in one of the modes, conditioned to the detection of any photon in the other mode. We show that photon subtraction does not produce nonclassical fields from classical fields. It is also derived a compact expression for the output field from which the calculation of conditional probabilities is straightforward for any input state. Examples include the analysis of squeezed-vacuum and odd-squeezed states. We also show that injecting optical cats into a beam splitter gives rise to entangled states in the Bell representation.

scholarly journals Single Photon Randomness based on a Defect Center in Diamond

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Xing Chen ◽  
Johannes N. Greiner ◽  
Jörg Wrachtrup ◽  
Ilja Gerhardt
Keyword(s):  
Beam Splitter ◽  
Single Photon ◽  
Photon Emission ◽  
Random Number Generator ◽  
Input State ◽  
Single Photons ◽  
Ambient Conditions ◽  
Single Photon Detector ◽  
Defect Center ◽  
Random Bit Generator

AbstractThe prototype of a quantum random number generator is a single photon which impinges onto a beam splitter and is then detected by single photon detectors at one of the two output paths. Prior to detection, the photon is in a quantum mechanical superposition state of the two possible outcomes with –ideally– equal amplitudes until its position is determined by measurement. When the two output modes are observed by a single photon detector, the generated clicks can be interpreted as ones and zeros – and a raw random bit stream is obtained. Here we implement such a random bit generator based on single photons from a defect center in diamond. We investigate the single photon emission of the defect center by an anti-bunching measurement. This certifies the “quantumness” of the supplied photonic input state, while the random “decision” is still based on the vacuum fluctuations at the open port of the beam-splitter. Technical limitations, such as intensity fluctuations, mechanical drift, and bias are discussed. A number of ways to suppress such unwanted effects, and an a priori entropy estimation are presented. The single photon nature allows for a characterization of the non-classicality of the source, and allows to determine a background fraction. Due to the NV-center’s superior stability and optical properties, we can operate the generator under ambient conditions around the clock. We present a true 24/7 operation of the implemented random bit generator.

scholarly journals Cooling of a Mechanical Oscillator and Normal Mode Splitting in Optomechanical Systems with Coherent Feedback

2019 ◽  
Vol 9 (16) ◽  
pp. 3402 ◽  
Author(s):  
Sumei Huang ◽  
Aixi Chen
Keyword(s):  
Normal Mode ◽  
Quantum Control ◽  
Beam Splitter ◽  
Mechanical Oscillator ◽  
Optomechanical System ◽  
Peak Separation ◽  
Mode Splitting ◽  
Feedback Scheme ◽  
Output Field ◽  
Normal Mode Splitting

The ground state cooling of a mechanical oscillator and strong optomechanical coupling are necessary prerequisites for realizing quantum control of the macroscopic mechanical oscillator. Here, we show that the resolved-sideband cooling of a mechanical oscillator in an optomechanical system can be enhanced by a simple coherent feedback scheme, in which a portion of the output field from the cavity is fed back into the cavity using an asymmetric beam splitter. Moreover, we show that the normal mode splitting in the spectra of the movable mirror and the output field in a weakly coupled optomechanical system can be induced by the feedback scheme due to a reduced effective cavity decay rate. We find that the peak separation becomes larger and two peaks of the spectra become narrower and higher with increasing the reflection coefficient r of the beam splitter.

scholarly journals Second-order temporal interference of two independent light beams at an asymmetrical beam splitter

2017 ◽  
Vol 26 (1) ◽  
pp. 014201 ◽  
Author(s):  
Jianbin Liu ◽  
Jingjing Wang ◽  
Zhuo Xu
Keyword(s):  
Beam Splitter ◽  
Second Order ◽  
Light Beams

scholarly journals Partial Bell-State Analysis with Parametric down Conversion in the Wigner Function Formalism

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
A. Casado ◽  
S. Guerra ◽  
J. Plácido
Keyword(s):  
Wigner Function ◽  
Beam Splitter ◽  
Bell State ◽  
Function Formalism ◽  
State Measurement ◽  
Parametric Down Conversion ◽  
Correlation Properties ◽  
Light Beams ◽  
Down Conversion ◽  
State Analysis

We apply the Wigner function formalism to partial Bell-state analysis using polarization entanglement produced in parametric down conversion. Two-photon statistics at a beam-splitter are reproduced by a wave-like description with zeropoint fluctuations of the electromagnetic field. In particular, the fermionic behaviour of two photons in the singlet state is explained from the invariance on the correlation properties of two light beams going through a balanced beam-splitter. Moreover, we show that a Bell-state measurement introduces some fundamental noise at the idle channels of the analyzers. As a consequence, the consideration of more independent sets of vacuum modes entering the crystal appears as a need for a complete Bell-state analysis.

scholarly journals Quantum optics experiment on the test of empty wave hypothesis

2019 ◽  
Author(s):  
Vladimir Skrebnev
Keyword(s):  
Quantum Optics ◽  
Beam Splitter ◽  
Single Photon ◽  
Single Photons ◽  
Absorption Coefficients ◽  
Empty Wave

The experiment measured the absorption of single photons by absorbers with various absorption coefficients, in one of the beams, after the photons interacted with the beam splitter. The measurements showed that the absorption corresponds to single photon traveling in either one or another beam. The measurements support the original empty wave hypothesis which has been advanced in a number of works.

Efficient Interaction of X-ray Single Photons with a Beam Splitter

2021 ◽  
Author(s):  
E. Strizhevsky ◽  
D. Borodin ◽  
A. Schori ◽  
S. Francoual ◽  
R. Röhlsberger ◽  
...  
Keyword(s):  
Beam Splitter ◽  
Single Photons ◽  
X Ray

scholarly journals Light on a beam splitter: More randomness with single photons

2015 ◽  
Vol 10 (1) ◽  
pp. 108-115 ◽  
Author(s):  
Lukas Oberreiter ◽  
Ilja Gerhardt
Keyword(s):  
Beam Splitter ◽  
Single Photons
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