Indefinite-Mean Pareto Photon Distribution from Amplified Quantum Noise

Motion of charged particles in bright squeezed vacuum

The motion of laser-driven electrons quivers with an average energy termed pondermotive energy. We explore electron dynamics driven by bright squeezed vacuum (BSV), finding that BSV induces width oscillations, akin to electron quivering in laser light, with an equivalent ponderomotive energy. We identify closed and open trajectories of the electronic width that are associated with high harmonic generation and above-threshold ionization, respectively, similarly to trajectories of the electron position when its motion is driven by coherent light. In the case of bound electrons, the width oscillations may lead to ionization with noisy sub-cycle structure. Our results are foundational for strong-field and free-electron quantum optics, as they shed light on ionization, high harmonic generation, and nonlinear Compton scattering in BSV.

Strong-Field Ionization of Hydrogen Atoms with Quantum Light

We study the strong-field ionization driven by quantum lights. Developing a quantum-optical-corrected strong-field approximation model, we simulate the photoelectron momentum distribution with squeezed-state light, which manifests as notably different interference structures from that with coherent-state (classical) light. With the saddle-point method, we analyze the electron dynamics and reveal that the photon statistics of squeezed-state light fields endows the tunneling electron wave packets with a time-varying phase uncertainty and modulates the photoelectron intracycle and intercycle interferences. Moreover, it is found the fluctuation of quantum light imprints significant influence on the propagation of tunneling electron wave packets, in which the ionization probability of electrons is considerably modified in time domain.

Extraction of unknown signals in arbitrary noise

We devise a general method to extract weak signals of unknown form, buried in noise of arbitrary distribution. Central to it is signal-noise decomposition in rank and time: only stationary white noise generates data with a jointly uniform rank-time probability distribution, U(1,N)×U(1,N), for N points in a data sequence. We show that rank, averaged across jointly indexed series of noisy data, tracks the underlying weak signal via a simple relation, for all noise distributions. We derive an exact analytic, distribution-independent form for the discrete covariance matrix of cumulative distributions for independent and identically distributed noise and employ its eigenfunctions to extract unknown signals from single time series.

Detection of unknown signals in arbitrary noise

We devise a simple method for detecting signals of unknown form buried in any noise, including heavy tailed. The method centers on signal-noise decomposition in rank and time: Only stationary white noise generates data with a jointly uniform rank-time probability distribution, U(1,N)×U(1,N), for N data points in a time series. Signals of any kind distort this uniformity. Such distortions are captured by rank-time cumulative distributions permitting all-purpose efficient detection, even for single time series and noise of infinite variance.

Controllable superbunching effect from four-wave mixing process in atomic vapor

Correlation property of light limits the performance in related applications such as the visibility of ghost imaging or intensity interferometry. To exceed these performance limits, we here manipulate the degree of second- and higher-order coherence of light by changing controllable variables in four-wave mixing (FWM) process. The measured degree of second- and third-order coherence of the output light beams considerably exceed those of the incident pseudothermal light. Namely superbunching effects, g⁽²⁾(0) value up to 7.47 and g⁽³⁾(0) value up to 58.34, are observed experimentally. In addition, strong second- and third-order cross-correlation exist between the output light beams. Further insights into the dependence of superbunching light on the temperature of Rb vapor, the laser detuning and the optical power of all the incident light beams show that it can serve as a light source with a tunable superbunching degree.

Accurate Detection of Arbitrary Photon Statistics

We report a measurement workflow free of systematic errors consisting of a reconfigurable photon-number-resolving detector, custom electronic circuitry, and faithful data-processing algorithm. We achieve an unprecedented accurate measurement of various photon-number distributions going beyond the number of detection channels with an average fidelity of 0.998, where the error is primarily caused by the sources themselves. Mean numbers of photons cover values up to 20 and faithful autocorrelation measurements range from g^{(2)}=6×10^{-3} to 2. We successfully detect chaotic, classical, nonclassical, non-Gaussian, and negative-Wigner-function light. Our results open new paths for optical technologies by providing full access to the photon-number information without the necessity of detector tomography.