Hanbury Brown And Twiss Research Articles

Hanbury-Brown–Twiss signature for clustered substructures probing primordial inhomogeneity in hot and dense QCD matter

We propose a novel approach to probe primordial inhomogeneity in hot and dense matter which could be realized in noncentral heavy-ion collisions. Although the Hanbury Brown and Twiss (HBT) interferometry is commonly used to infer the system size, the cluster size should be detected if substructures emerge in space. We demonstrate that a signal peak in the HBT two-particle correlation stands at the relative momentum corresponding to the spatial scale of pseudo one-dimensional modulation. We assess detectability using the data prepared by an event generator (AMPT model) with clustering implemented in the particle distribution. Published by the American Physical Society 2024

Photon noise correlations in millimeter-wave telescopes.

Many modern millimeter and submillimeter ("mm-wave") telescopes for astronomy are deploying more detectors by increasing the detector pixel density and, with the rise of lithographed detector architectures and high-throughput readout techniques, it is becoming increasingly practical to overfill the focal plane. However, when the pixel pitch p p i x is small compared to the product of the wavelength λ and the focal ratio F, or p p i x ≲1.2F λ, the Bose term of the photon noise correlates between neighboring detector pixels due to the Hanbury Brown and Twiss (HBT) effect. When this HBT effect is non-negligible, the array-averaged sensitivity scales with the detector count N det less favorably than the uncorrelated limit of Ndet-1/2. In this paper, we present a general prescription to calculate this HBT correlation based on a quantum optics formalism and extend it to polarization-sensitive detectors. We then estimate the impact of HBT correlations on the sensitivity of a model mm-wave telescope and discuss the implications for a focal plane design.

Combination of XEOL, TR-XEOL and HB-T interferometer at the TPS 23A X-ray nanoprobe for exploring quantum materials.

In this study, a combination of X-ray excited optical luminescence (XEOL), time-resolved XEOL (TR-XEOL) and the Hanbury-Brown and Twiss (HB-T) interferometer at the Taiwan Photon Source (TPS) 23A X-ray nanoprobe beamline for exploring quantum materials is demonstrated. On the basis of the excellent spatial resolution rendered using a nano-focused beam, emission distributions of artificial micro-diamonds can be obtained by XEOL maps, and featured emission peaks of a selected local area can be obtained by XEOL spectra. The hybrid bunch mode of the TPS not only provides a sufficiently high peak power density for experiments at each beamline but also permits high-quality temporal domain (∼200 ns) measurements for investigating luminescence dynamics. From TR-XEOL measurements, the decay lifetime of micro-diamonds is determined to be approximately 16 ns. Furthermore, the XEOL spectra of artificial micro-diamonds can be investigated by the HB-T interferometer to identify properties of single-photon sources. The unprecedented strategy of combining XEOL, TR-XEOL and the HB-T interferometer at the X-ray nanoprobe beamline will open new avenues with significant characterization abilities for unraveling the emission mechanisms of single-photon sources for quantum materials.

Minimum Variance Distortionless Response—Hanbury Brown and Twiss Sound Source Localization

Sound source target localization is an extremely useful technique that is currently utilized in many fields. The Hanbury Brown and Twiss (HBT) interference target localization method based on sound fields is not accurate enough for localization at low signal-to-noise ratios (below 0 dB). To address this problem, this paper introduces Minimum Variance Distortionless Response (MVDR) beamforming and proposes a new MVDR-HBT algorithm. Specifically, for narrowband signals, the inverse of the correlation matrix of the sound signal is calculated, and a guiding vector is constructed to compute the MVDR direction weights. These direction weights are then used to weight the correlation function of the HBT algorithm. Subsequently, the MVDR-HBT algorithm is extended from narrowband signals to broadband signals. As a result, the directivity of the HBT algorithm is optimized for wide- and narrowband signals, resulting in improved localization accuracy. Finally, the target localization accuracy of the MVDR-HBT algorithm is analyzed through simulation and localization experiments. The results show that the MVDR-HBT algorithm can accurately determine the direction of a sound source, with localization errors at different positions that are smaller than those produced by HBT. The localization performance of MVDR-HBT is considerably better than that of HBT, further verifying the simulation results. This study provides a new idea for target localization within an acoustic propagation medium (air).

Probing the topological character of superconductors via nonlocal Hanbury Brown and Twiss correlations

Superconductors can be classified as topological or not based on whether time-reversal symmetry, chiral symmetry, and particle-hole symmetry are preserved or not. Further, topological superconductors can also be classified as chiral or helical. In this paper, using Hanbury Brown and Twiss (HBT) shot-noise correlations and the nonlocal conductance, we probe metal and two-dimensional unconventional superconductor and metal junctions to understand better the pairing topological vs nontopological or helical vs chiral or nodal vs gapful. We see that HBT correlations are asymmetric as a function of bias voltage for nontopological superconductors, whereas they are symmetric for topological superconductors irrespective of the barrier strength. Topological superconductors are associated with Majorana fermions which are important for topological quantum computation. By distinguishing topological superconductors from nontopological superconductors, our study will help search for Majorana fermions, which will aid in designing a topological quantum computer.

Azimuthal-sensitive three-dimensional HBT radius in Au–Au collisions at $$E_{beam} = 1.23A$$ GeV by the IQMD model

We used an Isospin dependent Quantum Molecular Dynamics (IQMD) model to simulate Au + Au collisions at beam energy $$E_{beam}$$ = 1.23A GeV, which corresponds to center of mass energy $$\sqrt{s_{NN}} = 2.4$$ GeV. Firstly, we obtained reasonable rapidity and transverse mass spectra of $$\pi ^-$$ and $$\pi ^+$$ as well as “apparent” temperature parameters in comparison with the HADES data. Then by calculating three-dimensional Hanbury Brown and Twiss (HBT) radius of same charged pion-pairs, we obtained the square difference of outward radius and sideward radius, i.e. $$R_{out}^{2}-R_{side}^{2}$$ , as well as the freeze-out volume ( $$V_{fo}$$ ), which were basically consistent with the trend of HADES experimental results. The azimuthal dependence of the HBT radii was also calculated by a matrix method, and corrected by the rotation matrix. In addition, the eccentricities of the xy- and zy- planes of pion-pair emissions were also extracted for different pair transverse momentum and collision centrality, which show that the xy-eccentricity increases with pair transverse momentum as well as centrality but not for zy-eccentricity, indicating a more asymmetric transverse emission of particle-pairs with higher transverse momentum in off-central collisions.

Thermal biphotons

The observation of the Hanbury Brown and Twiss (HBT) effect with thermal light marked the birth of quantum optics. All the thermal sources considered to date did not feature quantum signatures of light, as they consisted of independent emitters that emit uncorrelated photons. Here, we propose and demonstrate an incoherent light source based on phase-randomized spatially entangled photons, which we coin thermal biphotons. We show that in contrast to thermal light, the width of the HBT peak for thermal biphotons is determined by their correlations, leading to violation of the Siegert relation and breakdown of the speckle-fluctuations interpretation. We further provide an alternative interpretation of the results by drawing a connection between the HBT effect and coherent backscattering of light. Finally, we discuss the role of spatial entanglement in the observed results, deriving a relation between the Schmidt number and the degree of violation of the Siegert relation under the double-Gaussian approximation of spontaneous parametric down conversion. Our work reflects new insights on the coherence properties of thermal light in the presence of entanglement, paving the way for entanglement certification using disorder averaged measurements.

Hanbury Brown and Twiss effect in the spatiotemporal domain II: the effect of spatiotemporal coupling

Spatiotemporal coupling is present when the electric fields of any pulsed beams fail to separate into a product of purely spatial and temporal factors, and it affects ultimately on the propagation of the light. Here we study the effect of spatiotemporal coupling on the Hanbury Brown and Twiss (HBT) effect for the first time, with the help of our recent developed method [Opt. Express 28, 32077 (2020)10.1364/OE.405726], by assuming the Gaussian statistics of partially coherent spatiotemporal pulsed sources containing the intensity and correlation coupling effect between the spatial and temporal domain. The generalized results for the spatiotemporal coupling HBT effect are investigated and through a nontrivial two-dimensional case, we numerically illustrate the influence of the spatiotemporal coupling on the HBT effect. It observes that even a very tiny coupling effect will strongly change the HBT effect at longer distances. This work will be potentially useful for the study of the HBT effect (intensity-intensity correlations) with dynamic sources having spatiotemporal coupling in both optics and other branches of physics.

Multi-focal laser fabrication of nitrogen vacancy centres in a bulk diamond

We demonstrate the multi-focal fabrication of single N V − centres at different depths in a bulk diamond. After performing an annealing process, the optically detected magnetic resonance (ODMR) signal is measured to confirm the generation of N V − centres. These emitters are photo-stable and are imaged by using three different excitations wavelengths at different depths close to the bulk diamond surface. Using two-photon microscopy, the N V − centres are imaged with a resolution down to 0.36 µm to study the effect of the exposure time of the multi-focal laser writing on the spatial resolution of each fabrication. The Hanbury Brown and Twiss (HBT) test is performed with two-photon excitation to study the number of N V − centres at the location of each multi-focal fabrication. We demonstrate the formation of single N V − centres placed between 100 nm and 3 µm below the diamond surface. The ability to control the placement of single N V − centres with depth is of paramount importance for applications in quantum information, single spin magnetometry, and optical data storage.

Hanbury Brown and Twiss Bunching of Phonons and of the Quantum Depletion in an Interacting Bose Gas.

We report the realization of a Hanbury Brown and Twiss (HBT)-like experiment with a gas of interacting bosons at low temperatures. The low-temperature regime is reached in a three-dimensional optical lattice and atom-atom correlations are extracted from the detection of individual metastable helium atoms after a long free fall. We observe, in the noncondensed fraction of the gas, a HBT bunching whose properties strongly deviate from the HBT signals expected for noninteracting bosons. In addition, we show that the measured correlations reflect the peculiar quantum statistics of atoms belonging to the quantum depletion and of the Bogoliubov phonons, i.e., of collective excitations of the many-body quantum state. Our results demonstrate that atom-atom correlations provide information about the quantum state of interacting particles, extending the interest of HBT-like experiments beyond the case of noninteracting particles.

Hanbury Brown and Twiss effect in spatiotemporal domain.

Hanbury Brown and Twiss (HBT) effect has broad applications in optics and other branches of physics, and traditionally this effect is considered in pure spatial or temporal domain. Here we investigate the spatiotemporal HBT effect, extending this phenomenon from spatial or temporal to spatiotemporal domain. By assuming the Gaussian statistics of partially coherent spatiotemporal pulsed sources, we find the generalized analytical results for spatiotemporal HBT effect in the compact form, with the help of the matrix-optics method, which can consider the HBT effect in spatial and temporal domain simultaneously. Furthermore, for Gaussian Schell-model pulsed beams (GSMPBs) used as a spatiotemporal correlated source, we have obtained the generalized expression to calculate spatiotemporal HBT effect, which is useful for up to three-dimensional cases in any second-order linear dispersive medium. By taking a simple two-dimensional case and using air as an example of a linear dispersive medium, we numerically illustrate the properties of the spatiotemporal HBT effect by adjusting the spatial and temporal parameters of the GSMPB source, and reveal the influence of both the spatial and temporal parameters on the spatiotemporal HBT effect. This work paves the path towards the detailed study of HBT effect for a source containing spatiotemporal information with Gaussian statistics.

Enhanced Hanbury Brown and Twiss interferometry using parametric amplification

The Hanbury Brown and Twiss (HBT) interferometer was proposed to observe intensity correlations of starlight to measure a star’s angular diameter. As the intensity of light that reaches the detector from a star is very weak, one cannot usually get a workable signal-to-noise ratio. We propose an improved HBT interferometric scheme incorporating optical parametric amplifiers (OPA) into the system to amplify the correlation signal. Remarkably, for weak star light, the signal-to-noise ratio (SNR) in the new HBT interferometric scheme is much better than that of conventional HBT interferometer. Our work is valuable in measuring a star whose intensity at the detector is low and maybe also applicable in remote sensing and long-distance quantum imaging where the light passed through the object is weak after a long distance transmission.

Hanbury Brown and Twiss exchange correlations in a graphene box

Quadratic detection in linear mesoscopic transport systems produces cross terms that can be viewed as interference signals reflecting statistical properties of charge carriers. In electronic systems these cross term interferences arise from exchange effects due to Pauli principle. Here we demonstrate fermionic Hanbury Brown and Twiss (HBT) exchange phenomena due to indistinguishability of charge carriers in a diffusive graphene system. These exchange effects are verified using current-current cross correlations in combination with regular shot noise (autocorrelation) experiments at microwave frequencies. Our results can be modeled using semiclassical analysis for a square-shaped metallic diffusive conductor, including contributions from contact transparency. The experimentally determined HBT exchange factor values lie between the calculated ones for coherent and hot electron transport.

Photon statistics of twisted heralded single photons

ABSTRACTWe study the correlation properties of single photons carrying orbital angular momentum (OAM) in a Hanbury Brown and Twiss (HBT) type experiment. We have characterized single photon sources obtained by pumping a nonlinear crystal with a laser beam carrying different OAM under same experimental conditions. For twisted heralded single photons carrying OAM, we calculate , a measurable parameter characterizing the quality of a single photon source, and observe an increment with the OAM of the single photon. The single photon behaviour of the heralded photons is observed to be reducing with higher orders of their OAM. An OAM-dependent variation of the photon statistics will be relevant to quantum information experiments involving twisted heralded single photons.

Direct Measurement of Non-Classical Photon Statistics with a Multi-Pixel Photon Counter

Photon number resolving detectors with high accuracy bring broad applications in long-distance laser ranging, ultrafast spectroscopy, and quantum optics. In this paper, we observed the non-classical photon number distribution directly with a multi-pixel photon counter (MPPC) instead of a classic Hanbury-Brown and Twiss (HBT) system. The detector’s photon-number resolving ability was characterized by quantum detector tomography. To show the quantum feature of the detector, we further plotted the Wigner function, which was obtained corresponding to the positive operator value measure (POVM) elements. Finally, we declared the observation of non-classical photon statistics from a single color center in nanodiamond by using this detector.

Lévy HBT Results at NA61/SHINE

Bose–Einstein (or Hanbury–Brown and Twiss (HBT)) momentum correlations reveal the space–time structure of the particle emitting source created in high energy nucleus–nucleus collisions. In this paper we present the latest NA61/SHINE measurements of Bose–Einstein correlations of identified pion pairs and their description based on Lévy distributed sources in Be + Be collisions at 150A GeV/c. We investigate the transverse mass dependence of the Lévy source parameters and discuss their possible interpretations.

Transverse revival and fractional revival of the Hanbury Brown and Twiss bunching effect with discrete chaotic light

We studied the Hanbury Brown and Twiss (HBT) bunching effect of discrete chaotic light sources. It is found that, for periodical discrete chaotic light sources, the HBT bunching effect collapses first but then revives repeatedly at specific transverse distances between two detectors in the far-field detection plane, which is very different from the HBT bunching effect with a spatially continuous chaotic light source. Such transverse revivals of the HBT bunching effect are the result of in-phase superposition of all discrete two-photon eigen modes of the periodical discrete chaotic light sources. In addition to the integer HBT bunching revival, the fractional HBT bunching revival can also be observed with nonperiodical discrete chaotic light sources due to the in-phase constructive interference of parts of the two-photon eigen modes. Experimental verification on both the integer and the fractional HBT bunching revivals are given. The transverse revival and fractional revival of the HBT bunching effect provide an efficient way for imaging processing such as ghost image copy in the detection plane.

Generalized Hanbury Brown-Twiss effect for Stokes parameters.

The classic experiments by Hanbury Brown and Twiss (HBT) were concerned with the correlation of intensity fluctuations at two different positions in a wave field. We generalize the HBT effect that occurs in random electromagnetic beams by examining its polarization-resolved version. This leads naturally to the concept of correlations of fluctuations of the four Stokes parameters. We calculate the correlations of such "Stokes fluctuations" for the case of Gaussian statistics. When the two points of observation coincide, these correlations reduce to "Stokes scintillations." Our work reveals a new layer of complexity in random beams by showing that the HBT effect and the scintillation coefficient are just two of many correlations that are present. We illustrate that, in general, the fluctuations of the various Stokes parameters are all correlated by studying beams and sources with different polarization states.

Non-invasive zero-delay time calibration of Hanbury-Brown and Twiss interferometers

Measuring photon autocorrelations via a Hanbury-Brown and Twiss (HBT) setup is a widely used experimental technique in quantum optics and is the base for quantum characterizations via Hong-Ou-Mandel interferometry, Bell inequality tests or quantum state tomography. The most common use for HBT measurements is the demonstration of single-photon emission from a quantum emitter. In order to make a definite statement and analyze the coincidence histograms obtained in the experiment, the temporal position of the zero delay time (ZDT) must be accurately known. In many cases, determining the ZDT requires tedious calibration measurements using light sources with known non-trivial photon correlations. Here we report on a non-invasive technique for measuring the ZDT in HBT setups based on avalanche photodiodes (APDs). The technique relies on the deliberate enhancement of optical crosstalk between the APDs. It can be used with any conventional laser source and therefore means a significant improvement for the easy calibration of the ZDT in HBT setups.

Hanbury-Brown and Twiss exchange and non-equilibrium-induced correlations in disordered, four-terminal graphene-ribbon conductor

We have investigated current-current correlations in a cross-shaped conductor made of graphene. The mean free path of charge carriers is on the order of the ribbon width which leads to a hybrid conductor where there is diffusive transport in the device arms while the central connection region displays near ballistic transport. Our data on auto and cross correlations deviate from the predictions of Landauer-Büttiker theory, and agreement can be obtained only by taking into account contributions from non-thermal electron distributions at the inlets to the semiballistic center, in which the partition noise becomes strongly modified. The experimental results display distinct Hanbury – Brown and Twiss (HBT) exchange correlations, the strength of which is boosted by the non-equilibrium occupation-number fluctuations internal to this hybrid conductor. Our work demonstrates that variation in electron coherence along atomically-thin, two-dimensional conductors has significant implications on their noise and cross correlation properties.