Antibunching Effect Research Articles

Tunable photon statistics in parametrically amplified photonic molecules

The proposal for single-photon generation utilizing quantum interference of two coupled cavity modes with weak Kerr nonlinearity under resonant coherent driving has been successfully put forward in previous work [T. C. H. Liew and V. Savona, Phys. Rev. Lett. 104, 183601 (2010)]. Here we suggest an alternative scheme to explore the statistical properties of the photons and their control in a parametrically amplified photonic molecule that is composed of a pair of coupled cavities, both containing the degenerate optical parametric amplifier (DOPA), by means of extending the model of Liew and Savona. Due to the destructive quantum interference effect between different paths for two-photon excitation, the photons in both cavity modes can exhibit a strong antibunching effect when one of the two cavities is coherently driven by an external laser field. In order to intuitively understand the strong photon antibunching phenomenon occurring in our DOPA photonic molecule, the approximate analytical solutions of the system are provided via the Schr\odinger equation and further are compared with the full numerical solutions via the master equation. The in-depth results reveal that the two solutions are in good agreement. For the two cavity modes, we achieve the optimal antibunching conditions in terms of the nonlinear gain and the strength ratio between the two pump laser fields based on analytical calculations, gaining deep insight into the rich physics of photon statistics. We also show that the statistical properties of the photons can be well controlled by regulating the relative phase between the two pump laser fields and the tunneling rate between the two cavity modes. Furthermore, we address the second-order cross-correlation function between the two cavity modes and find that a strong intermodal antibunching can be efficiently generated. Our approach via the DOPA photonic molecule architecture can be useful to generate tunable single-photon sources or controlled photonic quantum gates.

Temporal coherence of a photon condensate: A quantum trajectory description

In order to study the temporal coherence of a single-mode dye-cavity photon condensate, a model is developed for the dynamics which treats the condensate mode on a quantum-mechanical level. The effects of driving-dissipation and Kerr interactions on the number fluctuations are studied analytically and numerically, including the finding of a long-$\tau$ antibunching effect. Depending on the interaction strength, we quantitatively observe an exponential Schawlow-Townes-like decay or Gaussian Henry-like decay of phase correlations. The adequacy of a heuristic phasor model originating from laser physics in describing number and phase dynamics is validated within the experimentally relevant parameter regime. The ratio of the first and second order coherence times is shown to be inversely proportional to the number fluctuations, with a prefactor that varies smoothly throughout the crossover between canonical and grandcanonical statistics.

Phonon blockade in a nanomechanical resonator quadratically coupled to a two-level system

We investigate phonon statistics in a nanomechanical resonator (NAMR), which is quadratically coupled to a two-level system, by driving the NAMR and two-level system simultaneously. We find that unconventional phonon blockade (UCPNB), i.e., strong phonon antibunching effect based on quantum interference, can be observed when driven fields are weak. By increasing the strengths of the driving fields, we show the crossover from the UCPNB to the conventional phonon blockade (CPNB), which is induced by the strong nonlinear interaction of the system. Moreover, under the strong coupling condition for CPNB, quantum interference effect can also be used to enhanced the phonon blockade by optimizing the phase difference of the two external driving fields.

Two-mode Hadamard vacuum state and its properties

We investigate nonclassical properties of the quantum state generated by operating a two-mode Hadamard operator on the vacuum state. It is found that the scale length parameter of this new state plays an important role in squeezing. The anti-bunching effect, entanglement, and nonlocality are also derived analytically.

Decoherence of the two-mode squeezed vacuum state in a diffusion process

ABSTRACTWe have studied the case in which one mode of the light field in the two-mode squeezed vacuum state evolves in a diffusion channel. By virtue of thermo-entangled state representation and the technique of integration within an ordered product, the evolution formula of the field density operator is given. Its non-classical properties, such as squeezing effect, antibunching effect, the violation of Cauchy–Schwartze inequality and the entanglement property between two modes, are studied. The influences of the squeezing parameter and the dissipation time on the non-classical properties are discussed. The results obtained by the numerical method show that its non-classical properties are all weakened with the dissipation. On the other hand, its squeezing effect and the entanglement property between two modes are strengthened, but its antibunching effect and the violation of Cauchy–Schwartze inequality are weakened with the increase of the squeezing parameter.

Nonclassical properties of coherent state orthogonalization via Hermite polynomial excited operation

In this work, we theoretically construct an orthogonal state of a coherent state where the orthogonalizer is based on the Hermite polynomial excited operation with Hm(x) being a Hermite polynomial of order m and creation operator , called the Hermite-excite-orthogonalized coherent state (HEOCS). Then, in comparison with the Hermite polynomial excited coherent state (HPECS), we numerically investigate their different nonclassical properties by examining several measurable features, such as photon number distribution, sub-Poisson statistics, the antibunching effect, the quadrature squeezing effect, and the negative Wigner function. The results demonstrate that both HEOCS and HPECS are non-Gaussian quantum states with highly nonclassical characteristics by improving and modulating the order of the Hermite polynomial and coherent amplitude, which indicates that performing the Hermite-excited operation on given Gaussian states is an effective approach to generating non-Gaussian states.

Theoretical analysis of the length distributions of Ga-catalyzed GaAs nanowires

In this work, we analyze the length distributions of self-catalyzed GaAs nanowires grown on in-situ processed SiOx/Si(111) substrates. We propose the model that accounts for (i) gradual emerging of Ga droplets and nanowires, (ii) fluctuation-induced broadening of the length distributions, and (iii) the effect of nucleation antibunching in individual nanowires on the length distribution shapes. Both theoretical and experimental results show the broadest length distributions on unprocessed substrate, narrowing in samples with processed oxide surface and sub-Poissonian length distribution in samples with an optimized substrate preparation.

A Multichannel Time-Tagged Time-Resolved (TTTR) Model for Quantification of Oligomer Concentrations Based on Antibunching Effect.

Molecule/protein aggregation causes many devastating and incurable diseases in human bodies. For example, studies have revealed that protein oligomers formed at the early stage are toxic and may be mostly responsible for some diseases. In the fundamental research, differentiation of different protein oligomers and quantification of the concentrations are important and challenging. Here, we have developed a multichannel time-tagged time-resolved (TTTR) confocal fluorescence model based on antibunching effect to solve the problem. The key point of the model is that n-oligomers labeled with n-dyes cannot emit more than n photons at one time. By assuming that all labeling dyes behave perfectly as noninteractive individual dyes, the analytic relationship between photon-emission probability and oligomer concentrations has been derived. Simulations have been carried out to verify the model, in which differentiation and concentration quantification of up to tetraoligomers can be realized with a relative error <10% in an eight-channel TTTR confocal setup with eight single-photon detectors.

Orthogonalization of coherent state and generation of continuous-variable qubit state via a coherent superposition of photon addition and subtraction

Based on the coherent state (S1) and the operator [Formula: see text], we induce other three quantum states (here we abbreviate them as S2, S3 and S4). S2 is obtained by operating the operator on S1 directly. S3 is an orthogonal state of S1 constructed from the orthogonalizer relevant with that operator. S4 is a continuous-variable (CV) qubit state superposed from S1 and S3. We study and compare the mathematical and physical properties of such four quantum states. We demonstrate some statistical properties for S1–S4, including the mean photon number (MPN), anti-bunching effect, quadrate squeezing, photon number distribution, Husimi Q-function and Wigner function. The numerical results show some interesting non-classical characters for such states. It is worthy to note that the photon-added coherent state introduced by Agarwal and Tara is only a special case of our considered states.

Entangled nonlinear displaced number states

Entangled nonlinear displaced number states are defined as the superposition of separable two-mode nonlinear displaced number states. In this paper, the nonlinear functions related to the harmonious states and trapped ion motion in center of mass system are considered. Considering the importance of non-classical states in quantum information theory, the non-classical properties of these states, such as photon statistics and entanglement, will be studied. Photon statistics of the entangled nonlinear displaced number states is evaluated by calculating the Mandel parameter and second order coherence function; the entanglement of the states is also examined by calculating concurrence. According to calculations, all of the introduced states have sub-Poissonian photon statistics in some range of coherent amplitude where this range becomes larger by increasing the number of the photons, n. It was also observed that the quantum second-order coherence function of the maximally entangled states represent photon antibunching effect in all values of the related parameters.

Quantum Properties of the State via Operation of Superposition of Photon Subtraction Two Times and Photon Addition Two Times on Two Modes Squeezing Vacuum State

Superposition of photon subtraction two times and photon addition two times excited two modes squeezing vacuum state (SPSAESVT) is introduced, which is generated by operation of superposition of annihilation operator and creation operator on two modes squeezed vacuum state. Non-classical properties of SPSAESVT, such as squeezing effect, anti-bunching effect, the violation of Cauchy-Schwartze inequality and the entanglement property between two modes, are investigated. Using numerical methods, the influences of the superposition coefficient of operators and that of squeezing parameter on its non-classical properties are discussed. The results show that SPSAESVT does not display antibunching effect, but it displays squeezing effect, and there are the violation of Cauchy-Schwartze inequality and the entanglement between two modes. Further, its squeezing effect is not affected by the superposition coefficient of the operators, but there is a nonlinear relationship both between the violation of Cauchy-Schwartze inequality and the superposition coefficient, and between the entanglement property and the superposition coefficient. As squeezing parameter increases, its squeezing effect and entanglement property are strengthened, but the violation of Cauchy-Schwartze inequality is weakened.

Red Single-Photon Emission from InAs/AlGaAs Quantum Dots

We report on single-photon emission of InAs/AlGaAs self-assembled quantum dots (QDs) grown by molecular beam epitaxy. By varying the growth conditions the QDs luminescence could be tuned over a wide wavelength range from 0.64 to 1 μm, including red part of the visible spectrum. Emission properties of individual QDs are investigated by micro-photoluminescence (μ-PL) spectroscopy using 500-nm-size etched mesa structures. Autocorrelation functions of photons from single QDs, measured in the wide spectral range demonstrate antibunching effect at zero delay time with a value of g(2)(0) ~ 0.17 that is a clear evidence of non-classical light.

Optical properties of blue-green single-photon sources based on self-assembled CdSe quantum dots

We report on single photon emission with a wavelength below 500 nm from single CdSe quantum dots (QDs) grown by migration-enhanced epitaxy providing a reduced QD lateral density below 1010 cm-2. The QD photoluminescence was observed at the temperature of 8 K in 200-nm-wide mesa-structures made of CdSe QD heterostructures. The antibunching effect under cw excitation with g(2)(0) ˜ 0.2 was demonstrated.

Non-classical properties and polarization degree of photon-added entangled nonlinear coherent states

Photon-added states are introduced by applying creation operators of the two modes on the two-mode entangled nonlinear coherent states. These nonlinear coherent states are assumed to be harmonious. Then, non-classical properties of these states are examined by studying photon number distribution, Mandel parameter and second-order coherence function. Entanglement and quantum polarization of these states are also studied. We observe that all the states show sub-Poissonian statistics in some ranges of the parameters involved. In addition, the maximally entangled states show anti-bunching effect too. The dependence of the quantum polarization on the number of added photons and coherent amplitude is also evaluated.

Red single-photon emission from InAs/AlGaAs quantum dots

AbstractWe report on single-photon emission of InAs/AlGaAs self-assembled quantum dots (QDs) grown by molecular beam epitaxy. By varying the growth conditions the QDs luminescence could be tuned over a wide wavelength range from 0.64 to 1 μm, including red part of the visible spectrum. Emission properties of individual QDs are investigated by micro-photoluminescence (μ-PL) spectroscopy using 500-nm-size etched mesa structures. Autocorrelation functions of photons from single QDs, measured in the wide spectral range demonstrate antibunching effect at zero delay time with a value of g ^(2)(0) ~ 0.17 that is a clear evidence of non-classical light.

Unconventional phonon blockade in multimode optomechanical system

In this paper, we proposed to observe a phonon blockade in multimode optomechanical system. The multimode optomechanical system is consisting of one mechanical mode driven by a weakly mechanical field and two optical modes driven by two optical fields (a weak one and a strong one). Under the interaction of the strong optical driving field, the multimode optomechanical system can be reduced to a much simple model for a mechanical mode linearly coupled to an optical mode with Kerr nonlinearity. Our calculations show that strong phonon antibunching effects can be observed even with weak optomechanical coupling. This counter-intuitive phenomenon, i.e., unconventional phonon blockade, results from the destructive interference between different paths for two-phonon excitation and the optimal conditions for unconventional phonon blockade are obtained analytically. Moreover, the statistical properties of the phonons can be controlled by regulating the strength ratio and the relative phase between the weakly driving fields, and this provides us an effective way to realize tunable single-phonon sources. Finally, we show that the thermal phonons have a detrimental impact on the unconventional phonon blockade and a proper increase of the strengths of the weakly driving fields can be helpful to overcome the detrimental impact induced by the thermal phonons.

Formula omitted]-coherent states associated with the noncommutative complex plane [formula omitted] for the Biedenharn–Macfarlane [formula omitted]-oscillator

The q-coherent states associated with the noncommutative complex plane Cq2 for the Biedenharn–Macfarlane q-oscillator are constructed by using a q-generalization of the Glauber’s unitary displacement operator. The q-deformed counterpart of the eigenvalue equation of undeformed harmonic oscillator coherent states is obtained. Some properties of the q-coherent states are considered. It is shown that super-Poissonian statistics and saturation of the uncertainty relation occur simultaneously with the nonclassical behaviors including antibunching effects with nonnegative values less than unity and the negative values, for the second-order intensity q-correlation function in the case of q>1. Furthermore, the nonclassical sub-Poissonian statistics is demonstrated simultaneously with bunching and antibunching effects such that in some regions of the coherence parameter the uncertainty inequality is satisfied, and violated elsewhere. We show that another nonclassical effect, the so-called strong squeezing effect, is exhibited by both quadrature variances in the latter issue.

Phonon antibunching effect in coupled nonlinear micro/nanomechanical resonator at finite temperature

In this study, we investigate the phonon antibunching effect in a coupled nonlinear micro/nanoelectromechanical system (MEMS/NEMS) resonator at a finite temperature. In the weak driving limit, the optimal condition for phonon antibunching is given by solving the stationary Liouville-von Neumann master equation. We show that at low temperature, the phonon antibunching effect occurs in the regime of weak nonlinearity and mechanical coupling, which is confirmed by analytical and numerical solutions. We also find that thermal noise can degrade or even destroy the antibunching effect for different mechanical coupling strengths. Furthermore, a transition from strong antibunching to bunching for phonon correlation has been observed in the temperature domain. Finally, we find that a suitably strong driving in the finite-temperature case would help to preserve an optimal phonon correlation against thermal noise.

Few-photon scattering on Bose-Hubbard lattices

We theoretically investigate the scattering of few-photon light on Bose-Hubbard lattices using diagrammatic scattering theory. We explicitly derive general analytical expressions for the lowest-order photonic correlation functions, which we apply numerically to several different lattices. We focus specifically on nonlinear effects visible in the intensity-intensity correlation function and explain bunching and antibunching effects in dimers, chains, rings, and planes. The numerical implementation can be applied to arbitrary Bose-Hubbard graphs, and we provide it as an attachment to this publication.

Sub-Poissonian length distributions of vapor–liquid–solid nanowires induced by nucleation antibunching

Herein, we present an analytic length distribution of vapor–liquid–solid nanowires growing without the nucleation delays of the very first monolayer, by the direct impingement of material from vapor, and in the absence of desorption. We show that nucleation antibunching narrows the Poissonian length distribution to a time-independent asymptotic shape. The obtained distribution depends on the sole control parameter describing the effect of antibunching, and has a variance of rather than spreading infinitely with time. A good agreement is found between the analytic shapes obtained within the continuum growth theory and Green’s function of the discrete rate equations describing the length statistics of nanowires. Overall, this narrowing effect can be used to improve the size homogeneity of III–V and other semiconductor nanowires grown under the appropriate conditions.