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Quantum nanophotonics merges the precision of nanoscale light manipulation with the capabilities of quantum technologies, offering a pathway for enhanced light-matter interaction and compact realization of quantum devices. Here, we show how…

Spontaneous emission and the inelastic scattering of photons are two natural processes usually associated with decoherence and the reduction in the capacity to process quantum information. Here we show that when suitably detected, these…

Quantum Physics · Physics 2012-04-27 Marcelo F. Santos , Marcelo Terra Cunha , Rafael Chaves , Andre R. R. Carvalho

Quantum networks require interfacing stationary and flying qubits. These flying qubits are usually nonclassical states of light. Here we consider two of the leading source technologies for nonclassical light, spontaneous parametric…

Quantum gates are the building blocks of quantum circuits, which in turn are the cornerstones of quantum information processing. In this work, we theoretically investigate a single-step implementation of both a universal two- (CNOT) and…

Quantum Physics · Physics 2024-07-01 Luiz O. R. Solak , Daniel Z. Rossatto , Celso J. Villas-Boas

Single photons produced by fundamentally dissimilar physical processes will in general not be indistinguishable. We show how photons produced from a quantum dot and by parametric down-conversion in a nonlinear crystal can be manipulated to…

Quantum entanglement across spatially separated network nodes is conventionally established through the distribution of photons from a common source or via entanglement swapping that relies on Bell-state measurements and pre-shared…

Quantum Physics · Physics 2026-01-06 Sören Arlt , Mario Krenn , Xuemei Gu

We show how techniques from machine learning and optimization can be used to find circuits of photonic quantum computers that perform a desired transformation between input and output states. In the simplest case of a single input state,…

Efficient teleportation is a crucial step for quantum computation and quantum networking. In the case of qubits, four different entangled Bell states have to be distinguished. We have realized a probabilistic, but in principle…

Quantum Physics · Physics 2009-11-10 Philip Walther , Anton Zeilinger

Entanglement has evolved from an enigmatic concept of quantum physics to a key ingredient of quantum technology. It explains correlations between measurement outcomes that contradict classical physics, and has been widely explored with…

Quantum Physics · Physics 2024-06-05 Philip Thomas , Leonardo Ruscio , Olivier Morin , Gerhard Rempe

Four-qubit cluster states of two photons entangled in polarization and linear momentum have been used to realize a complete set of single qubit rotations and the C-NOT gate for equatorial qubits with high values of fidelity. By the…

Quantum Physics · Physics 2015-05-13 Giuseppe Vallone , Enrico Pomarico , Francesco De Martini , Paolo Mataloni

When two indistinguishable single photons are fed into the two input ports of a beam splitter, the photons will coalesce and leave together from the same output port. This is a quantum interference effect, which occurs because the two…

Semiconductor quantum dots (QDs) have emerged as a premier solid-state platform for the deterministic generation of nonclassical light, offering a compelling pathway toward scalable quantum photonic systems. While single-photon emission…

Optics · Physics 2026-02-06 Xingling Pan , Zhiming Chen , Yingtao Ding , Weibo Gao , Fei Ding , Zhaogang Dong

Quantum entanglement -- correlations of particles that are stronger than any classical analogue -- is the basis for research on the foundations of quantum mechanics and for practical applications such as quantum networks. Traditionally,…

Quantum Physics · Physics 2024-12-05 Kai Wang , Zhaohua Hou , Kaiyi Qian , Leizhen Chen , Mario Krenn , Shining Zhu , Xiao-song Ma

We present a conceptually new approach to describe state-of-the-art photonic quantum experiments using Graph Theory. There, the quantum states are given by the coherent superpositions of perfect matchings. The crucial observation is that…

Quantum Physics · Physics 2019-03-08 Xuemei Gu , Manuel Erhard , Anton Zeilinger , Mario Krenn

The future of integrated quantum photonics relies heavily on the ability to engineer refined methods for preparing the quantum states needed to implement various quantum protocols. An important example of such states are quantum-correlated…

Quantum Physics · Physics 2018-02-28 Jesper B. Christensen , Jacob G. Koefoed , Karsten Rottwitt , Colin. J. McKinstrie

Systems of linear equations are used to model a wide array of problems in all fields of science and engineering. Recently, it has been shown that quantum computers could solve linear systems exponentially faster than classical computers,…

Universal quantum entangling gates are a crucial building block in the large-scale quantum computation and quantum communication, and it is an important task to find simple ways to implement them. Here an effective quantum circuit for the…

Quantum Physics · Physics 2022-03-31 Wen-Qiang Liu , Hai-Rui Wei , Leong-Chuan Kwek

We present a quantum interference phenomenon in which four-photon quantum states generated by two independent sources are used to create a two-photon interference pattern without detecting two of the photons. Contrary to the common…

Quantum Physics · Physics 2025-09-26 Chandler Tarrant , Mayukh Lahiri

We discuss the use of the transverse spatial degrees of freedom of photons propagating in the paraxial approximation for continuous variable information processing. Given the wide variety of linear optical devices available, a diverse range…

Quantum Physics · Physics 2011-06-16 D. S. Tasca , R. M. Gomes , F. Toscano , P. H. Souto Ribeiro , S. P. Walborn

A single three-level atom driven by a longitudinal mode of a high-Q cavity is used to implement two-qubit quantum phase gates for the intracavity field. The two qubits are associated to the zero-and one-photon Fock states of each of the two…

Quantum Physics · Physics 2016-08-16 R. García--Maraver , R. Corbalán , K. Eckert , S. Rebić , M. Artoni , J. Mompart