Bracket states for communication protocols with coherent states

We present the generation and characterization of the class of bracket states, namely phase-sensitive mixtures of coherent states exhibiting symmetry properties in the phase-space description. A bracket state can be seen as the statistical ensemble arriving at a receiver in a typical coherent-state-based communication channel. We show that when a bracket state is mixed at a beam splitter with a local oscillator, both the emerging beams exhibit a Fano factor larger than 1 and dependent on the relative phase between the input state and the local oscillator. We discuss the possibility to exploit this dependence to monitor the phase difference for the enhancement of the performances of a simple communication scheme based on direct detection. Our experimental setup involves linear optical elements and a pair of photon-number-resolving detectors operated in the mesoscopic photon-number domain.

Download Full-text

Homodyne-like detection scheme based on photon-number-resolving detectors

International Journal of Quantum Information ◽

10.1142/s0219749917400160 ◽

2017 ◽

Vol 15 (08) ◽

pp. 1740016 ◽

Cited By ~ 5

Author(s):

Alessia Allevi ◽

Matteo Bina ◽

Stefano Olivares ◽

Maria Bondani

Keyword(s):

Coherent States ◽

Beam Splitter ◽

Photon Number ◽

Local Oscillator ◽

Quantum States ◽

Homodyne Detection ◽

Detection Scheme ◽

Light Signals ◽

The Difference ◽

Signal Field

Homodyne detection is the most effective detection scheme employed in quantum optics to characterize quantum states. It is based on mixing at a beam splitter the signal to be measured with a coherent state, called the “local oscillator,” and on evaluating the difference of the photocurrents of two photodiodes measuring the outputs of the beam splitter. If the local oscillator is much more intense than the field to be measured, the homodyne signal is proportional to the signal-field quadratures. If the local oscillator is less intense, the photodiodes can be replaced with photon-number-resolving detectors, which have a smaller dynamics but can measure the light statistics. The resulting new homodyne-like detector acquires a hybrid nature, being it capable of yielding information on both the particle-like (statistics) and wave-like (phase) properties of light signals. The scheme has been tested in the measurement of the quadratures of coherent states, bracket states and phase-averaged coherent states at different intensities of the local oscillator.

Download Full-text

Continuous Variable Entanglement in Non-Zero Orbital Angular Momentum States

Proceedings ◽

10.3390/proceedings2019012007 ◽

2019 ◽

Vol 12 (1) ◽

pp. 7

Author(s):

Adriana Pecoraro ◽

Filippo Cardano ◽

Lorenzo Marrucci ◽

Alberto Porzio

Keyword(s):

Angular Momentum ◽

Orbital Angular Momentum ◽

Direct Detection ◽

Hybrid Approach ◽

Photon Number ◽

Local Oscillator ◽

Continuous Variable ◽

Degree Of Freedom ◽

Entangled State ◽

Continuous Variables

Orbital angular momentum is a discrete degree of freedom that can access an infinite dimensional Hilbert space, thus enhancing the information capacity of a single optical beam. Continuous variables field quadratures allow achieving some quantum tasks in a more advantageous way with respect to the use of photon-number states. Here, we use a hybrid approach realizing bipartite continuous-variable Gaussian entangled state made up of two electromagnetic modes carrying orbital angular momentum. A q-plate is used for endowing a pair of entangled beams with such a degree of freedom. This quantum state is then completely characterized thanks to a novel design of a homodyne detector in which also the local oscillator is an orbital angular momentum-carrying beams so allowing the direct detection of vortex modes quadratures.

Download Full-text

Engineering Schrödinger cat states with a photonic even-parity detector

Quantum ◽

10.22331/q-2020-03-02-239 ◽

2020 ◽

Vol 4 ◽

pp. 239 ◽

Cited By ~ 5

Author(s):

G. S. Thekkadath ◽

B. A. Bell ◽

I. A. Walmsley ◽

A. I. Lvovsky

Keyword(s):

Time Reversal ◽

Coherent States ◽

Beam Splitter ◽

Photon Number ◽

Input State ◽

Interference Phenomenon ◽

Arbitrary Size ◽

Two Component ◽

Schrödinger Cat ◽

Cat States

When two equal photon-number states are combined on a balanced beam splitter, both output ports of the beam splitter contain only even numbers of photons. Consider the time-reversal of this interference phenomenon: the probability that a pair of photon-number-resolving detectors at the output ports of a beam splitter both detect the same number of photons depends on the overlap between the input state of the beam splitter and a state containing only even photon numbers. Here, we propose using this even-parity detection to engineer quantum states containing only even photon-number terms. As an example, we demonstrate the ability to prepare superpositions of two coherent states with opposite amplitudes, i.e. two-component Schrödinger cat states. Our scheme can prepare cat states of arbitrary size with nearly perfect fidelity. Moreover, we investigate engineering more complex even-parity states such as four-component cat states by iteratively applying our even-parity detector.

Download Full-text

Equation for a Composite Scalar Particle in (2+1)-D and its Solutions

Modern Physics Letters A ◽

10.1142/s0217732397001734 ◽

1997 ◽

Vol 12 (23) ◽

pp. 1699-1708 ◽

Cited By ~ 2

Author(s):

S. I. Kruglov

Keyword(s):

Wave Function ◽

Electromagnetic Wave ◽

Coherent States ◽

Dimensional Space ◽

Plane Electromagnetic Wave ◽

Photon Number ◽

Scalar Particle ◽

Linearly Polarized ◽

External Electromagnetic Fields ◽

Quantized Electromagnetic Field

A model of a scalar particle in (2+1)-dimensional space with an internal structure in external electromagnetic fields is considered. Exact solutions of the equation for such scalar particle were obtained in the field of a plane electromagnetic wave with the arbitrary polarization and in the quantized electromagnetic field of the linearly polarized wave. The relativistic coherent states of the particle in the field of n photons were constructed. When the photon number goes to infinity, this wave function transforms to the solution corresponding to the external classical electromagnetic wave.

Download Full-text

Nonclassicality of photon-modulated spin coherent states in the Holstein-Primakoff realization

Chinese Physics B ◽

10.1088/1674-1056/ac40f5 ◽

2021 ◽

Author(s):

Xiaoyan Zhang ◽

Jisuo Wang ◽

Lei Wang ◽

Xiangguo Meng ◽

Baolong Liang

Keyword(s):

Coherent States ◽

Wigner Distribution ◽

Hermite Polynomials ◽

Photon Number ◽

Spin Ladder ◽

Bernoulli Distribution ◽

Ladder Operators ◽

Spin Number ◽

Photon Number Distribution ◽

Spin Coherent States

Abstract Two new photon-modulated spin coherent states (SCSs) are introduced by operating the spin ladder operators J ± on the ordinary SCS in the Holstein-Primakoff realization and the nonclassicality is exhibited via their photon number distribution, second-order correlation function, photocount distribution and negativity of Wigner distribution. Analytical results show that the photocount distribution is a Bernoulli distribution and the Wigner functions are only associated with two-variable Hermite polynomials. Compared with the ordinary SCS, the photon-modulated SCSs exhibit more stronger nonclassicality in certain regions of the photon modulated number k and spin number j, which means that the nonclassicality can be enhanced by selecting suitable parameters.

Download Full-text

Local oscillator-less QPSK signal detection using direct detection and fractional Fourier transform

10.1364/oecc.2021.m3a.2 ◽

2021 ◽

Author(s):

Ryohei Kamikawa ◽

Yu Yamasaki ◽

Tsuyoshi Konishi

Keyword(s):

Fourier Transform ◽

Signal Detection ◽

Fractional Fourier Transform ◽

Direct Detection ◽

Local Oscillator

Download Full-text

Gaussian and Non-Gaussian operations on non-Gaussian state: engineering non-Gaussianity

Quantum Measurements and Quantum Metrology ◽

10.2478/qmetro-2014-0001 ◽

2014 ◽

Vol 2 (1) ◽

Author(s):

Stefano Olivares ◽

Alessia Allevi ◽

Maria Bondani

Keyword(s):

Coherent State ◽

Direct Detection ◽

The State ◽

Gaussian State ◽

Classical State ◽

Phase Sensitive ◽

Photon Subtraction ◽

Non Gaussian

AbstractMultiple photon subtraction applied to a displaced phase-averaged coherent state, which is a non-Gaussian classical state, produces conditional states with a non trivial (positive) Glauber-Sudarshan Prepresentation. We theoretically and experimentally demonstrate that, despite its simplicity, this class of conditional states cannot be fully characterized by direct detection of photon numbers. In particular, the non-Gaussianity of the state is a characteristics that must be assessed by phase-sensitive measurements. We also show that the non-Gaussianity of conditional states can be manipulated by choosing suitable conditioning values and composition of phase-averaged states.

Download Full-text

On the Squeezing and Displacement of nth-Order

Modern Physics Letters B ◽

10.1142/s0217984997000499 ◽

1997 ◽

Vol 11 (09n10) ◽

pp. 399-406

Author(s):

Norton G. de Almeida ◽

Célia M. A. Dantas

Keyword(s):

Coherent State ◽

Coherent States ◽

Photon Number ◽

Natural Generalization ◽

Statistical Properties ◽

Number Distribution ◽

Quantum Statistical ◽

Photon Number Distribution

The norder expressions for the squeezed and coherent states are derived as a natural generalization of the usual squeezed coherent and coherent states. The photon number distribution of n order of squeezed coherent states that are eigenstates of the operators [Formula: see text] is derived. The n order coherent state is a particular case of the states that we are now deriving. Some mathematical and quantum statistical properties of these states are discussed.

Download Full-text

Generalized Binomial Probability Distributions Attached to Landau Levels on the Riemann Sphere

Advances in Mathematical Physics ◽

10.1155/2011/393417 ◽

2011 ◽

Vol 2011 ◽

pp. 1-17

Author(s):

A. Ghanmi ◽

A. Hafoud ◽

Z. Mouayn

Keyword(s):

Coherent States ◽

Riemann Sphere ◽

Probability Distributions ◽

Photon Number ◽

Landau Levels ◽

Binomial Probability ◽

Statistical Parameters ◽

Generalized Coherent States

A family of generalized binomial probability distributions attached to Landau levels on the Riemann sphere is introduced by constructing a kind of generalized coherent states. Their main statistical parameters are obtained explicitly. As an application, photon number statistics related to coherent states under consideration are discussed.

Download Full-text