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Path entanglement constitutes an essential resource in quantum information and communication protocols. Here, we demonstrate frequency-degenerate entanglement between continuous-variable quantum microwaves propagating along two spatially…

To quantify the effect of decoherence in quantum measurements, it is desirable to measure not merely the square modulus of the spatial wavefunction, but the entire density matrix, whose phases carry information about momentum and how pure…

Quantum Physics · Physics 2009-10-30 Max Tegmark

We study the emergence of two types of two-photon bounds states in waveguides of any chirality. Specifically, we present a systematic way of analytically determining the eigenstates of a system consisting of a waveguide coupled to a…

Quantum Physics · Physics 2021-10-13 Bastian Bakkensen , Yu-Xiang Zhang , Johannes Bjerlin , Anders Søndberg Sørensen

A localized qubit entangled with a propagating quantum field is well suited to study non-local aspects of quantum mechanics and may also provide a channel to communicate between spatially separated nodes in a quantum network. Here, we…

Quantum Physics · Physics 2013-01-29 C. Eichler , C. Lang , J. M. Fink , J. Govenius , S. Filipp , A. Wallraff

We propose an interferometric method to investigate the non-locality of high-dimensional two-photon orbital angular momentum states generated by spontaneous parametric down conversion. We incorporate two half-integer spiral phase plates and…

Quantum Physics · Physics 2007-05-23 A. Aiello , S. S. R. Oemrawsingh , E. R. Eliel , J. P. Woerdman

We perform state tomography of an itinerant squeezed state of the microwave field prepared by a Josephson parametric amplifier (JPA). We use a second JPA as a pre-amplifier to improve the quantum efficiency of the field quadrature…

An entangled quantum state is considered by applying a local photon excitation to each mode of an entangled coherent state. The entanglement property is investigated in terms of the entropy of entanglement. It is shown that applying a…

Quantum Physics · Physics 2023-04-13 Arpita Chatterjee

In this paper we investigate the coupling properties of pairs of quadrature observables, showing that, apart from the Weyl relation, they share the same coupling properties as the position-momentum pair. In particular, they are…

Quantum Physics · Physics 2015-05-14 Pekka Lahti , Juha-Pekka Pellonpaa

We study the quantum correlations of the radiation emitted by three level atoms (cascade type) interacting with two driving fields. In the linear regime, and in the Weisskopf-Wigner approximation, we show that the atomic and the two-photon…

Quantum Physics · Physics 2010-12-30 S. N. Sandhya , V. Ravishankar

Entangled microwave photons form a fundamental resource for quantum information processing and sensing with continuous variables. We use a low-loss Josephson metamaterial comprising superconducting, non-linear, asymmetric inductive elements…

In molecular aggregates, multiple delocalized exciton states interact with phonons, making the state-resolved spectroscopic monitoring of dynamics challenging. We propose a protocol that combines photon-entanglement-enhanced narrowband…

Quantum Physics · Physics 2026-04-24 Arunangshu Debnath , Shaul Mukamel

Entanglement is the quintessential quantum mechanical phenomenon understood to lie at the heart of future quantum technologies and the subject of fundamental scientific investigations. Mixture, resulting from noise, is often an unwanted…

Two-mode squeezed states, which are entangled states with bipartite quantum correlations in continuous-variable systems, are crucial in quantum information processing and metrology. Recently, continuous-variable quantum computing with the…

Quantum Physics · Physics 2023-11-10 Wui Seng Leong , Mingjie Xin , Zilong Chen , Yu Wang , Shau-Yu Lan

Quantum states of light can improve imaging whenever the image quality and resolution are limited by the quantum noise of the illumination. In the case of a bright illumination, quantum enhancement is obtained for a light field composed of…

Quantum Physics · Physics 2015-07-13 C. S. Embrey , M. T. Turnbull , P. G. Petrov , V. Boyer

We demonstrate a new technique for characterizing two-photon quantum states based on joint temporal correlation measurements using time resolved single photon detection by femtosecond upconversion. We measure for the first time the joint…

Quantum Physics · Physics 2009-11-13 Onur Kuzucu , Franco N. C. Wong , Sunao Kurimura , Sergey Tovstonog

Conditional preparation of photon number states from a continuous-wave nondegenerate optical parametric oscillator is investigated. We derive the phase space Wigner function for the output state conditioned on photo detection events that…

Quantum Physics · Physics 2007-06-07 Anne E. B. Nielsen , Klaus Molmer

Photons entangled in their position-momentum degrees of freedom (DoFs) serve as an elegant manifestation of the Einstein-Podolsky-Rosen paradox, while also enhancing quantum technologies for communication, imaging, and computation. The…

We analyze the quantum dynamics of two electromagnetic oscillators coupled in series to a voltage biased Josephson junction. When the applied voltage leads to a Josephson frequency across the junction which matches the sum of the two mode…

Mesoscale and Nanoscale Physics · Physics 2015-06-10 A. D. Armour , Björn Kubala , Joachim Ankerhold

We show that spatial entanglement of two twin images obtained by parametric down-conversion is complete, i.e. concerns both amplitude and phase. This is realised through a homodyne detection of these images which allows for measurement of…

Quantum Physics · Physics 2007-05-23 Enrico Brambilla , Alessandra Gatti , Patrick Navez , Luigi A. Lugiato

A measurement scheme to perform a repeatable phase detection on a two-mode field is presented. The interaction with the probe state (the output state of a phase-insensitive high-gain amplifier) is described by a Hamiltonian which is…

Quantum Physics · Physics 2013-10-29 G. M. D'Ariano , M. F. Sacchi