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Continuous-variable quantum information, encoded into infinite-dimensional quantum systems, is a promising platform for the realization of many quantum information protocols, including quantum computation, quantum metrology, quantum…

Quantum Physics · Physics 2021-06-17 Ya-Dong Wu , Ge Bai , Giulio Chiribella , Nana Liu

Machine learning is a fascinating and exciting field within computer science. Recently, this excitement has been transferred to the quantum information realm. Currently, all proposals for the quantum version of machine learning utilize the…

Quantum Physics · Physics 2017-02-28 Hoi-Kwan Lau , Raphael Pooser , George Siopsis , Christian Weedbrook

The characterization of a quantum device is a crucial step in the development of quantum experiments. This is accomplished via Quantum Process Tomography, which combines the outcomes of different projective measurements to deliver a…

Quantum Physics · Physics 2025-06-26 Francesco Di Colandrea , Nazanin Dehghan , Alessio D'Errico , Ebrahim Karimi

We show that coherent harmonic focusing provides an efficient mechanism to boost all-optical signatures of quantum vacuum nonlinearity in the collision of high-intensity laser fields, thereby offering a promising route to their first…

High Energy Physics - Phenomenology · Physics 2020-07-28 Felix Karbstein , Alexander Blinne , Holger Gies , Matt Zepf

Recent progress in photonic information processing has spurred strong demand in scalable and reconfigurable photonic circuitry. Conventional spatially-meshed multi-port interferometers require a number of components growing quadratically…

Quantum Physics · Physics 2026-04-08 Jasvith Raj Basani , Chaohan Cui , Jack Postlewaite , Edo Waks , Saikat Guha

We implement an all-optical setup demonstrating kernel-based quantum machine learning for two-dimensional classification problems. In this hybrid approach, kernel evaluations are outsourced to projective measurements on suitably designed…

We present an experimental implementation of a two-qubit photonic quantum processor fabricated using femtosecond laser writing technology. We employ femtosecond laser writing to create a low-loss reconfigurable photonic chip implementing…

Quantum information processing has the potential to substantially enhance how we learn from physical experiments, but coupling a quantum processor to an experimental sample introduces noise that can exponentially degrade learning even when…

Quantum Physics · Physics 2026-05-05 Ishaan Kannan , Harald Putterman , Jordan Cotler

Conditional quantum optical processes enable a wide range of technologies from generation of highly non-classical states to implementation of quantum logic operations. The process fidelity that can be achieved in a realistic implementation…

Quantum Physics · Physics 2015-06-23 Merlin Cooper , Eirion Slade , Michal Karpinski , Brian J. Smith

Parity measurement is a central tool to many quantum information processing tasks. In this Letter, we propose a method to directly measure two- and four-qubit parity with low overhead in hard- and software, while remaining robust to…

Quantum communication devices, such as quantum repeaters, quantum memories, or quantum channels, are unavoidably exposed to imperfections. However, the presence of imperfections can be tolerated, as long as we can verify such devices retain…

Quantum Physics · Physics 2011-05-26 Nathan Killoran , Norbert Lütkenhaus

The certification of randomness is essential for both fundamental science and information technologies. Unlike traditional random number generators, randomness obtained from nonlocal correlations is fundamentally guaranteed to be…

Quantum correlations in composite and separable quantum systems are characterized by non-vanishing quantum discord. We demonstrate the necessary and sufficient conditions for existence of hermitian witness operators for quantum discord,…

Quantum Physics · Physics 2013-01-01 S. Adhikari , A. S. Majumdar , I. Chakraborty

Targeting at the realization of scalable photonic quantum technologies, the generation of many photons, their propagation in large optical networks, and a subsequent detection and analysis of sophisticated quantum correlations are essential…

The implementation of large-scale universal quantum computation represents a challenging and ambitious task on the road to quantum processing of information. In recent years, an intermediate approach has been pursued to demonstrate quantum…

Quantum technology is poised to enable a step change in human capability for computing, communications and sensing. Photons are indispensable as carriers of quantum information - they travel at the fastest possible speed and readily…

We introduce a general method for the construction of quasiprobability representations for arbitrary notions of quantum coherence. Our technique yields a nonnegative probability distribution for the decomposition of any classical state.…

Quantum Physics · Physics 2018-06-22 J. Sperling , I. A. Walmsley

Quantum computers promise to efficiently solve not only problems believed to be intractable for classical computers, but also problems for which verifying the solution is also considered intractable. This raises the question of how one can…

Quantum Physics · Physics 2018-07-10 Alexandru Gheorghiu , Theodoros Kapourniotis , Elham Kashefi

Reliable encoding of information in quantum systems is crucial to all approaches to quantum information processing or communication. This applies in particular to photons used in linear optics quantum computing (LOQC), which is scalable…

Quantum Physics · Physics 2013-07-02 Peter B. R. Nisbet-Jones , Jerome Dilley , Annemarie Holleczek , Oliver Barter , Axel Kuhn

Hybrid encoding of quantum information is a promising approach towards the realisation of optical quantum protocols. It combines advantages of continuous variables encoding, such as high efficiencies, with those of discrete variables, such…

Quantum Physics · Physics 2021-01-04 G. Masse , T. Coudreau , A. Keller , P. Milman