Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1512.00768 · Physical Review A

Measurement-induced long-distance entanglement of superconducting qubits using optomechanical transducers

Ondřej Černotík, Klemens Hammerer

Published Jul 25, 2016• 30 citations
arXivHTMLPDF

Abstract

Although superconducting systems provide a promising platform for quantum computing, their networking poses a challenge because they cannot be interfaced to light, the medium used to send quantum signals through channels at room temperature. We show that mechanical oscillators can mediate such coupling and light can be used to measure the joint state of two distant qubits. The measurement provides information on the total spin of the two qubits such that entangled qubit states can be postselected. Entanglement generation is possible without ground-state cooling of the mechanical oscillators for systems with optomechanical cooperativity moderately larger than unity; in addition, our setup tolerates a substantial transmission loss. The approach is scalable to the generation of multipartite entanglement and represents a crucial step towards quantum networks with superconducting circuits.

DOI
10.1103/physreva.94.012340

Related papers

Interfacing Superconducting Qubits with Light

Piero Chiappina

Superconducting quantum circuits are a leading hardware candidate for realizing a large-scale fault-tolerant quantum computer. However, scaling superconducting quantum computers will soon approach the physical limits imposed by their cryogenic operating environments. Consequently, interconnects between multiple processor modules will become increasingly necessary for scaling quantum computers. Optical fiber is a particularly promising candidate for these interconnects due to its low loss and negligible thermal noise at room temperature. However, interfacing microwave-frequency superconducting circuits with optical fibers presents several challenges. In this thesis, we present a modular architecture which addresses many of the current challenges in building this interface. We develop an optomechanical quantum transducer which is capable of generating microwave- and optical-frequency photons in pairs, and demonstrate quantum entanglement between these microwave-optical photon pairs. Further, we develop a superconducting qubit module optimized for efficient absorption of itinerant microwave photons, and demonstrate a high-efficiency photon catch protocol. Finally, we connect the superconducting qubit module to the transducer module via a superconducting microwave cable. We drive the microwave-optical photon pair generation process in the transducer module and employ the photon catch protocol in the qubit module to facilitate state transfer between the qubit and the flying microwave photon from the transducer. We observe correlations between the final qubit state and the detection of an optical photon, demonstrating a crucial step toward establishing quantum entanglement between superconducting qubits and light. We discuss ongoing progress and challenges in realizing hybrid entanglement and in extending this approach to entangle remote superconducting qubits over optical networks.

•Aug 19, 2026•0 citations

Efficient Entanglement of Spin Qubits Mediated by a Hot Mechanical Oscillator

Emma Rosenfeld, Ralf Riedinger, Jan Gieseler +2 more

Localized electronic and nuclear spin qubits in the solid state constitute a promising platform for storage and manipulation of quantum information, even at room temperature. However, the development of scalable systems requires the ability to entangle distant spins, which remains a challenge today. We propose and analyze an efficient, heralded scheme that employs a parity measurement in a decoherence free subspace to enable fast and robust entanglement generation between distant spin qubits mediated by a hot mechanical oscillator. We find that high-fidelity entanglement at cryogenic and even ambient temperatures is feasible with realistic parameters and show that the entangled pair can be subsequently leveraged for deterministic controlled-NOT operations between nuclear spins. Our results open the door for novel quantum processing architectures for a wide variety of solid-state spin qubits.

arXiv:2011.02623•Physical Review Letters•Jun 24, 2021•23 citations

Optically heralded microwave photons

Wentao Jiang, Felix M. Mayor, Sultan Malik +5 more

A quantum network that distributes and processes entanglement would enable powerful new computers and sensors. Optical photons with a frequency of a few hundred terahertz are perhaps the only way to distribute quantum information over long distances. Superconducting qubits on the other hand, which are one of the most promising approaches for realizing large-scale quantum machines, operate naturally on microwave photons that have roughly $40,000$ times less energy. To network these quantum machines across appreciable distances, we must bridge this frequency gap and learn how to generate entanglement across widely disparate parts of the electromagnetic spectrum. Here we implement and demonstrate a transducer device that can generate entanglement between optical and microwave photons, and use it to show that by detecting an optical photon we add a single photon to the microwave field. We achieve this by using a gigahertz nanomechanical resonance as an intermediary, and efficiently coupling it to optical and microwave channels through strong optomechanical and piezoelectric interactions. We show continuous operation of the transducer with $5\%$ frequency conversion efficiency, and pulsed microwave photon generation at a heralding rate of $15$ hertz. Optical absorption in the device generates thermal noise of less than two microwave photons. Joint measurements on optical photons from a pair of transducers would realize entanglement generation between distant microwave-frequency quantum nodes. Improvements of the system efficiency and device performance, necessary to realize a high rate of entanglement generation in such networks are within reach.

arXiv:2210.10739•Oct 19, 2022•5 citations

Entangling Two Superconducting Microwave Qubits Over Optical Fiber – Progress Towards Optimization and Implementation

Rau, Curtis Lloyd

Quantum networks linking quantum computers are predicted to be extremely useful for a wide range of applications. At the hardware level, superconducting quantum computers have emerged as one of the most promising scalable platforms for general quantum computation, and optical networks are clearly the best choice for long distance communication due to their minimal loss. To leverage the strengths of these two dissimilar platforms, quantum transducers, which are reachingquantum-enabled operation, are needed. This thesis presents progress towards designing a long distance optical network which will entangle two superconducting qubits and the implementation of the optical portion of this network. We have found simple, application independent, necessary and sufficient conditions for transducers to work in quantum networks, and we conclude that some previously demonstrated devices are ready for integration into a quantum network. Optimizing the integration of two transducers into a network is explored and it is found that the most robust topology to transmission loss consists of generating optical Gaussian entanglement and then using the two transducers to down-convert this entanglement to the microwave domain. To implement this topology we have constructed a tunable source of optical two-mode squeezing and two ultra-low noise photodetectors. Finally a new method for transferring and distilling Gaussian entanglement to qubits using the dispersive Jaynes-Cummings interaction is presented. This proof-of-principle two-node network should be able to entangle superconducting qubits at a rate of 5 ebits/second over 4 km of optical fiber using currently available technology.

•Jul 27, 2023•0 citations

Optomechanical Transducers for Long-Distance Quantum Communication

Kai Stannigel, Peter Rabl, Anders Søndberg Sørensen +2 more

We describe a new scheme to interconvert stationary and photonic qubits which is based on indirect qubit-light interactions mediated by a mechanical resonator. This approach does not rely on the specific optical response of the qubit and thereby enables optical quantum interfaces for a wide range of solid state spin and charge based systems. We discuss the implementation of state transfer protocols between distant nodes of a quantum network and show that high transfer fidelities can be achieved under realistic experimental conditions.

arXiv:1006.4361•Physical Review Letters•Nov 23, 2010•459 citations

Cavity piezo-mechanics for superconducting-nanophotonic quantum interface

Xu Han, Wei Fu, Changchun Zhong +8 more

Abstract Hybrid quantum systems are essential for the realization of distributed quantum networks. In particular, piezo-mechanics operating at typical superconducting qubit frequencies features low thermal excitations, and offers an appealing platform to bridge superconducting quantum processors and optical telecommunication channels. However, integrating superconducting and optomechanical elements at cryogenic temperatures with sufficiently strong interactions remains a tremendous challenge. Here, we report an integrated superconducting cavity piezo-optomechanical platform where 10 GHz phonons are resonantly coupled with photons in a superconducting cavity and a nanophotonic cavity at the same time. Taking advantage of the large piezo-mechanical cooperativity (Cem ~7) and the enhanced optomechanical coupling boosted by a pulsed optical pump, we demonstrate coherent interactions at cryogenic temperatures via the observation of efficient microwave-optical photon conversion. This hybrid interface makes a substantial step towards quantum communication at large scale, as well as novel explorations in microwave-optical photon entanglement and quantum sensing mediated by gigahertz phonons.

arXiv:2001.09483•Nature Communications•Jun 26, 2020•122 citations
Although superconducting systems provide a promising platform for quantum computing, their networking poses a challenge because they cannot be interfaced to light, the medium used to send quantum signals through channels at room temperature. We show that mechanical oscillators can mediate such coupling and light can be used to measure the joint state of two distant qubits. The measurement provides information on the total spin of the two qubits such that entangled qubit states can be postselected. Entanglement generation is possible without ground-state cooling of the mechanical oscillators for systems with optomechanical cooperativity moderately larger than unity; in addition, our setup tolerates a substantial transmission loss. The approach is scalable to the generation of multipartite entanglement and represents a crucial step towards quantum networks with superconducting circuits.
Superconducting quantum circuits are a leading hardware candidate for realizing a large-scale fault-tolerant quantum computer. However, scaling superconducting quantum computers will soon approach the physical limits imposed by their cryogenic operating environments. Consequently, interconnects between multiple processor modules will become increasingly necessary for scaling quantum computers. Optical fiber is a particularly promising candidate for these interconnects due to its low loss and negligible thermal noise at room temperature. However, interfacing microwave-frequency superconducting circuits with optical fibers presents several challenges. In this thesis, we present a modular architecture which addresses many of the current challenges in building this interface. We develop an optomechanical quantum transducer which is capable of generating microwave- and optical-frequency photons in pairs, and demonstrate quantum entanglement between these microwave-optical photon pairs. Further, we develop a superconducting qubit module optimized for efficient absorption of itinerant microwave photons, and demonstrate a high-efficiency photon catch protocol. Finally, we connect the superconducting qubit module to the transducer module via a superconducting microwave cable. We drive the microwave-optical photon pair generation process in the transducer module and employ the photon catch protocol in the qubit module to facilitate state transfer between the qubit and the flying microwave photon from the transducer. We observe correlations between the final qubit state and the detection of an optical photon, demonstrating a crucial step toward establishing quantum entanglement between superconducting qubits and light. We discuss ongoing progress and challenges in realizing hybrid entanglement and in extending this approach to entangle remote superconducting qubits over optical networks.
Localized electronic and nuclear spin qubits in the solid state constitute a promising platform for storage and manipulation of quantum information, even at room temperature. However, the development of scalable systems requires the ability to entangle distant spins, which remains a challenge today. We propose and analyze an efficient, heralded scheme that employs a parity measurement in a decoherence free subspace to enable fast and robust entanglement generation between distant spin qubits mediated by a hot mechanical oscillator. We find that high-fidelity entanglement at cryogenic and even ambient temperatures is feasible with realistic parameters and show that the entangled pair can be subsequently leveraged for deterministic controlled-NOT operations between nuclear spins. Our results open the door for novel quantum processing architectures for a wide variety of solid-state spin qubits.
A quantum network that distributes and processes entanglement would enable powerful new computers and sensors. Optical photons with a frequency of a few hundred terahertz are perhaps the only way to distribute quantum information over long distances. Superconducting qubits on the other hand, which are one of the most promising approaches for realizing large-scale quantum machines, operate naturally on microwave photons that have roughly 40,00040,00040,000 times less energy. To network these quantum machines across appreciable distances, we must bridge this frequency gap and learn how to generate entanglement across widely disparate parts of the electromagnetic spectrum. Here we implement and demonstrate a transducer device that can generate entanglement between optical and microwave photons, and use it to show that by detecting an optical photon we add a single photon to the microwave field. We achieve this by using a gigahertz nanomechanical resonance as an intermediary, and efficiently coupling it to optical and microwave channels through strong optomechanical and piezoelectric interactions. We show continuous operation of the transducer with 5%5\%5% frequency conversion efficiency, and pulsed microwave photon generation at a heralding rate of 151515 hertz. Optical absorption in the device generates thermal noise of less than two microwave photons. Joint measurements on optical photons from a pair of transducers would realize entanglement generation between distant microwave-frequency quantum nodes. Improvements of the system efficiency and device performance, necessary to realize a high rate of entanglement generation in such networks are within reach.
Quantum networks linking quantum computers are predicted to be extremely useful for a wide range of applications. At the hardware level, superconducting quantum computers have emerged as one of the most promising scalable platforms for general quantum computation, and optical networks are clearly the best choice for long distance communication due to their minimal loss. To leverage the strengths of these two dissimilar platforms, quantum transducers, which are reachingquantum-enabled operation, are needed. This thesis presents progress towards designing a long distance optical network which will entangle two superconducting qubits and the implementation of the optical portion of this network. We have found simple, application independent, necessary and sufficient conditions for transducers to work in quantum networks, and we conclude that some previously demonstrated devices are ready for integration into a quantum network. Optimizing the integration of two transducers into a network is explored and it is found that the most robust topology to transmission loss consists of generating optical Gaussian entanglement and then using the two transducers to down-convert this entanglement to the microwave domain. To implement this topology we have constructed a tunable source of optical two-mode squeezing and two ultra-low noise photodetectors. Finally a new method for transferring and distilling Gaussian entanglement to qubits using the dispersive Jaynes-Cummings interaction is presented. This proof-of-principle two-node network should be able to entangle superconducting qubits at a rate of 5 ebits/second over 4 km of optical fiber using currently available technology.
We describe a new scheme to interconvert stationary and photonic qubits which is based on indirect qubit-light interactions mediated by a mechanical resonator. This approach does not rely on the specific optical response of the qubit and thereby enables optical quantum interfaces for a wide range of solid state spin and charge based systems. We discuss the implementation of state transfer protocols between distant nodes of a quantum network and show that high transfer fidelities can be achieved under realistic experimental conditions.
Abstract Hybrid quantum systems are essential for the realization of distributed quantum networks. In particular, piezo-mechanics operating at typical superconducting qubit frequencies features low thermal excitations, and offers an appealing platform to bridge superconducting quantum processors and optical telecommunication channels. However, integrating superconducting and optomechanical elements at cryogenic temperatures with sufficiently strong interactions remains a tremendous challenge. Here, we report an integrated superconducting cavity piezo-optomechanical platform where 10 GHz phonons are resonantly coupled with photons in a superconducting cavity and a nanophotonic cavity at the same time. Taking advantage of the large piezo-mechanical cooperativity (Cem ~7) and the enhanced optomechanical coupling boosted by a pulsed optical pump, we demonstrate coherent interactions at cryogenic temperatures via the observation of efficient microwave-optical photon conversion. This hybrid interface makes a substantial step towards quantum communication at large scale, as well as novel explorations in microwave-optical photon entanglement and quantum sensing mediated by gigahertz phonons.