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Correlations and entanglement between itinerant microwave photons created in a cascaded decay

Simone Gasparinetti, Marek Pechal, Jean-Claude Besse +3 more

Bulletin of the American Physical SocietyMar 16, 20170 citations

Quantum computing with itinerant microwave photons

Janne I. Kokkala

Jan 1, 20131 citation

Generating and verifying entangled itinerant microwave fields with efficient and independent measurements

H. S. Ku, William Kindel, F. Mallet +5 more

By combining a squeezed propagating microwave field and an unsqueezed vacuum field on a hybrid (microwave beam splitter), we generate entanglement between the two output modes. We verify that we have generated entangled states by making independent and efficient single-quadrature measurements of the two output modes. We observe the entanglement witness ${E}_{\mathrm{W}}=\ensuremath{-}0.{263}_{\ensuremath{-}0.036}^{+0.001}$ and the negativity $N=0.{0824}_{\ensuremath{-}0.0004}^{+0.01}$ with measurement efficiencies at least $26\ifmmode\pm\else\textpm\fi{}0.1%$ and $41\ifmmode\pm\else\textpm\fi{}0.2%$ for channels 1 and 2, respectively. These measurements show that the output two-mode state violates the separability criterion and therefore demonstrates entanglement. This shared entanglement between propagating microwaves provides an important resource for building quantum networks with superconducting microwave systems.By combining a squeezed propagating microwave field and an unsqueezed vacuum field on a hybrid (microwave beam splitter), we generate entanglement between the two output modes. We verify that we have generated entangled states by making independent and efficient single-quadrature measurements of the two output modes. We observe the entanglement witness ${E}_{\mathrm{W}}=\ensuremath{-}0.{263}_{\ensuremath{-}0.036}^{+0.001}$ and the negativity $N=0.{0824}_{\ensuremath{-}0.0004}^{+0.01}$ with measurement efficiencies at least $26\ifmmode\pm\else\textpm\fi{}0.1%$ and $41\ifmmode\pm\else\textpm\fi{}0.2%$ for channels 1 and 2, respectively. These measurements show that the output two-mode state violates the separability criterion and therefore demonstrates entanglement. This shared entanglement between propagating microwaves provides an important resource for building quantum networks with superconducting microwave systems.

arXiv:1502.03884Physical Review AApr 8, 201527 citations

Entanglement Between Microwave Photons Through a Spin Ensemble

A. Asghari Nejad, Hassan Randjbar Askari

International Journal of Theoretical PhysicsApr 1, 20221 citation

Quantifying distributable and unconditional entanglement at microwave frequencies

Hsiang‐Sheng Ku, William Kindel, Scott Glancy +5 more

Bulletin of the American Physical SocietyMar 2, 20120 citations

Emission and Absorption of Microwave Photons in Orthogonal Temporal Modes across a 30-Meter Two-Node Network

Alonso Hernández-Antón, Josua D. Schär, Aleksandr Grigorev +6 more

The tunable interaction between stationary quantum bits and propagating modes of light allows for the encoding of quantum information in the state of itinerant photons. This ability fulfills a central requirement for quantum networking, enabling quantum state transfer between distant quantum devices. Conventionally, a symmetric envelope of the photon wavepacket is used for such purposes. Yet, the use of alternative \textit{temporal modes} enables multiple applications in waveguide quantum electrodynamics that remain unexplored experimentally. Here, we use superconducting quantum circuits to generate individual itinerant microwave photons shaped in three mutually orthogonal temporal modes. We transfer the created photons across a 30-m cryogenic link, showing that the orthogonality allows us to decide at the receiver which mode to absorb, reflecting the other two with a selectivity ratio of 40. This experimental capability extends the microwave-frequency quantum communication toolbox, enabling a new photonic degree of freedom.The tunable interaction between stationary quantum bits and propagating modes of light allows for the encoding of quantum information in the state of itinerant photons. This ability fulfills a central requirement for quantum networking, enabling quantum state transfer between distant quantum devices. Conventionally, a symmetric envelope of the photon wavepacket is used for such purposes. Yet, the use of alternative \textit{temporal modes} enables multiple applications in waveguide quantum electrodynamics that remain unexplored experimentally. Here, we use superconducting quantum circuits to generate individual itinerant microwave photons shaped in three mutually orthogonal temporal modes. We transfer the created photons across a 30-m cryogenic link, showing that the orthogonality allows us to decide at the receiver which mode to absorb, reflecting the other two with a selectivity ratio of 40. This experimental capability extends the microwave-frequency quantum communication toolbox, enabling a new photonic degree of freedom.

quant-pharXiv:2604.12947Apr 15, 20260 citations

Generating and verifying entanglement of itinerant microwave modes

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