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In this contribution we analyze virtual-state spectroscopy --- a unique tool for extracting information about the virtual states that contribute to the two-photon excitation of an absorbing medium --- as implemented by means of intense…

Quantum Physics · Physics 2018-03-14 Jiří Svozilík , Jan Peřina , Roberto de J. León-Montiel

Control over the internal states of trapped ions makes them the ideal system to generate single and two-photon states. Coupling a single ion to an optical cavity enables efficient emission of single photons into a single spatial mode and…

Quantum Physics · Physics 2026-01-26 Ian Ford , Adrien Amour , Matthias Keller

We report a novel quantum random number generator based on the photon-number$-$path entangled state which is prepared via two-photon quantum interference at a beam splitter. The randomness in our scheme is of truly quantum mechanical origin…

Quantum Physics · Physics 2009-03-18 Osung Kwon , Young-Wook Cho , Yoon-Ho Kim

Decay of a four-level diamond scheme via a cascade is a potential source of entangled photon pairs. A solid-state implementation is the biexciton cascade in a semiconductor quantum dot. While high entanglement fidelities have been…

We investigate the practicality of the method proposed by Maciel et al. [Phys. Rev. A. 80, 032325(2009)] for detecting the entanglement of two spatial qutrits (3-dimensional quantum systems), which are encoded in the discrete transverse…

Quantum Physics · Physics 2015-05-18 G. Lima , E. S. Gómez , A. Vargas , R. O. Vianna , C. Saavedra

Quantum state tomography, a fundamental tool for quantum physics, usually requires a number of state copies that scale exponentially with the system size, owing to the intricate quantum correlations between subsystems. We show that, in…

Quantum Physics · Physics 2025-12-22 Xiaobin Zhao , Pengcheng Liao , Francesco Anna Mele , Ulysse Chabaud , Quntao Zhuang

Photons are natural carriers of quantum information due to their ease of distribution and long lifetime. This thesis concerns various related aspects of quantum information processing with single photons. Firstly, we demonstrate N-photon…

Quantum Physics · Physics 2007-05-23 Yuan Liang Lim

Using the type-I SPDC process in BBO nonlinear crystal (NLC), we generate a polarization-entangled state near to the maximally-entangled Bell-state with high-visibility (high-brightness) $ 98.50 \pm 1.33 ~ \% $ ($ 87.71 \pm 4.45 ~ \% $) for…

Quantum Physics · Physics 2021-07-06 Ali Motazedifard , Seyed Ahmad Madani , N. S. Vayaghan

High-dimensional entanglement is a valuable resource for quantum communication, and photon pairs entangled in orbital angular momentum are commonly used for encoding high-dimensional quantum states. However, methods for preparation of…

Quantum Physics · Physics 2018-12-19 Egor Kovlakov , Stanislav Straupe , Sergey Kulik

We present an experimentally feasible and efficient method for detecting entangled states with measurements that extend naturally to a tomographically complete set. Our detection criterion is based on measurements from subsets of a quantum…

Quantum Physics · Physics 2019-01-30 Joonwoo Bae , Beatrix C. Hiesmayr , Daniel McNulty

Two-electron charged self-assembled quantum dot molecules exhibit a decoherence-avoiding singlet-triplet qubit subspace and an efficient spin-photon interface. We demonstrate quantum entanglement between emitted photons and the spin-qubit…

Mesoscale and Nanoscale Physics · Physics 2017-12-27 Yves L. Delley , Martin Kroner , Stefan Fält , Werner Wegscheider , Ataç İmamoğlu

Path identiy induces a broad interest in recent years due to the foundation for numerous novel quantum information applications. Here, we experimentally demonstrate quantum coherent superposition of two different origins of a four-photon…

The Hong-Ou-Mandel interference between independent photons plays a pivotal role in the large-scale quantum networks involving distant nodes. Photons need to work in a pure state for indistinguishability to reach high-quality interference.…

Quantum Physics · Physics 2023-07-03 Bo Li , Yu-Huai Li , Yuan Cao , Juan Yin , Cheng-Zhi Peng

Recent investigations suggest that the use of non-classical states of light, such as entangled photon pairs, may open new and exciting avenues in experimental two-photon absorption spectroscopy. Despite several experimental studies of…

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

Quantum entanglement, one of the defining features of quantum mechanics, has been demonstrated in a variety of nonlinear spin-like systems. Quantum entanglement in linear systems has proven significantly more challenging, as the intrinsic…

Hyperentangled photonic states - exhibiting nonclassical correlations in several degrees of freedom - offer improved performance of quantum optical communication and computation schemes. Experimentally, a hyperentanglement of…

Quantum Physics · Physics 2021-06-21 Michał Lipka , Michał Parniak

We demonstrate the ability to extract a spin-entangled state of two neutral atoms via postselection based on a measurement of their spatial configuration. Typically, entangled states of neutral atoms are engineered via atom-atom…

We propose and demonstrate a method for quantum-state tomography of qudits encoded in the quantum polarization of $N$-photon states. This is achieved by distributing $N$ photons nondeterministically into three paths and their subsequent…

Quantum Physics · Physics 2016-09-14 Ömer Bayraktar , Marcin Swillo , Carlota Canalias , Gunnar Björk

Entangled photons are a crucial resource for quantum communication and linear optical quantum computation. Unfortunately, the applicability of many photon-based schemes is limited due to the stochastic character of the photon sources.…

Quantum Physics · Physics 2012-02-07 Stefanie Barz , Gunther Cronenberg , Anton Zeilinger , Philip Walther