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Interference between an unknown two-photon state (a "biphoton") and the two-photon component of a reference state gives a phase-sensitive arrival-time distribution containing full information about the biphoton temporal wave function. Using…

We present a single-photon-sensitive spectrometer, based on a linear array of 512 single-photon avalanche diode detectors, with 0.04 nm spectral and 40 ps temporal resolutions. We employ a fast data-driven operation that allows direct…

To fully utilize the energy-time degree of freedom of photons for optical quantum information processes, it is necessary to control and characterize the quantum states of the photons at extremely short time scales. For measurements beyond…

Quantum Physics · Physics 2012-03-27 Changliang Ren , Holger F. Hofmann

The standard method of "measuring" quantum wavefunction is the technique of {\it indirect} quantum state tomography. Owing to conceptual novelty and possible advantages, an alternative {\it direct} scheme was proposed and demonstrated…

Quantum Physics · Physics 2023-09-26 Lupei Qin , Luting Xu , Wei Feng , Xin-Qi Li

The temporal degree-of-freedom of light is incredibly powerful for modern quantum technologies, enabling large-scale quantum computing architectures and record key-rates in quantum key distribution. However, the generalized measurement of…

The physical interpretation of weak measurements has been the subject of much debate. It is known that anomalous phenomena and results that appear in weak measurements are essentially related to the phase of the quantum system being…

Quantum Physics · Physics 2024-10-29 Nobuharu Nakajima

We propose a method to directly measure the complex phase distribution, superfluid density and velocity field in an ultracold atomic superfluid. The method consists of mapping the momentum distribution of the gas to real space using…

Quantum Gases · Physics 2019-11-26 Puneet A. Murthy , Selim Jochim

Time-bin encoding is a robust form of optical quantum information, especially for transmission in optical fibers. To read out the information, the separation of the time bins must be larger than the detector time resolution, typically on…

Quantum Physics · Physics 2014-10-17 John M. Donohue , Megan Agnew , Jonathan Lavoie , Kevin J. Resch

Joint spectral measurements are a powerful tool for characterising biphoton spectral correlation, which is crucial for quantum information and communication technologies. In these applications, highly pure biphoton states are essential in…

Long-distance quantum communication relies on storing and retrieving photonic qubits in orthogonal field modes. The available degrees of freedom for photons are polarization, spatial-mode profile, and temporal/spectral profile. To date,…

Quantum Physics · Physics 2015-06-18 Dileep V. Reddy , Michael G. Raymer , Colin J. McKinstrie

A photon is the single excitation of a particular spatiotemporal mode of the electromagnetic field. A precise knowledge of the mode structure is therefore essential for its processing and detection, as well as for applying generic quantum…

Nonlinear frequency conversion provides an elegant method to detect photons in a spectral range which differs from the pump wavelength, making it highly attractive for photons with inherently low energy. Aside from the intensity of the…

Optics · Physics 2022-02-10 Tobias Pfeiffer , Jens Klier , Georg von Freymann , Daniel Molter

Precise measurements are the key to advances in all fields of science. Quantum entanglement shows higher sensitivity than achievable by classical methods. Most physical quantities including position, displacement, distance, angle, and…

Quantum Physics · Physics 2017-07-05 Zhi-Yuan Zhou , Shi-Long Liu , Shi-Kai Liu , Yin-Hai Li , Dong-Sheng Ding , Guang-Can Guo , Bao-Sen Shi

Digital camera pixels measure image intensities by converting incident light energy into an analog electrical current, and then digitizing it into a fixed-width binary representation. This direct measurement method, while conceptually…

Computer Vision and Pattern Recognition · Computer Science 2021-04-13 Atul Ingle , Trevor Seets , Mauro Buttafava , Shantanu Gupta , Alberto Tosi , Mohit Gupta , Andreas Velten

We present a technique to completely characterise the spectral-temporal wave function of a broadband photon pair using spectral-shearing interferometry. Our method is fully self-referencing and is generalisable across a wide range of…

Quantum Physics · Physics 2018-09-12 Alex O. C. Davis , Valerian Thiel , Brian J. Smith

We propose a very simple experimental setup to measure, via photon counting, the overlap of the Wigner functions characterizing two single mode light beams. We show that this scheme can be applied to determine directly the phase space…

atom-ph · Physics 2009-10-28 Konrad Banaszek , Krzysztof Wodkiewicz

Since the birth of quantum optics, the measurement of quantum states of nonclassical light has been of tremendous importance for advancement in the field. To date, conventional detectors such as photomultipliers, avalanche photodiodes, and…

Quantum Physics · Physics 2026-01-30 Alexey Gorlach , Aviv Karnieli , Raphael Dahan , Eliahu Cohen , Avi Pe'er , Ido Kaminer

Generation and control of quantum states of light on an integrated platform has become an essential tool for scalable quantum technologies. Chip scale sources such as nonlinear optical microcavities have been demonstrated to efficiently…

Optics · Physics 2019-11-13 Usman A. Javid , Steven D. Rogers , Austin Graf , Qiang Lin

We demonstrate that time-domain ptychography, a recently introduced ultrafast pulse reconstruction modality, has properties ideally suited for the temporal characterization of complex light pulses with large time-bandwidth products as it…

We consider the estimation of a Hamiltonian parameter of a set of highly photosensitive samples, which are damaged after a few photons $N_{\rm abs}$ are absorbed, for a total time $T$. The samples are modelled as a two mode photonic system,…

Quantum Physics · Physics 2021-04-28 M. Perarnau-Llobet , D. Malz , J. I. Cirac