We investigate how quantum measurements affect the dynamics of quantum correlations of the system which consists of two noninteracting superconducting qubits each locally coupling to its own data bus. It is shown that the geometric discord and entanglement between two superconducting qubits can be increased by applying a sequence of selective measurements. The optimal measurement time at which the quantum correlations achieve their maximal values is also analyzed. Moreover, we find that the selective measurements on the data buses can protect quantum information of two superconducting qubits and force information to flow back to the superconducting qubits from the data buses by a witness of the trace distance.We investigate how quantum measurements affect the dynamics of quantum correlations of the system which consists of two noninteracting superconducting qubits each locally coupling to its own data bus. It is shown that the geometric discord and entanglement between two superconducting qubits can be increased by applying a sequence of selective measurements. The optimal measurement time at which the quantum correlations achieve their maximal values is also analyzed. Moreover, we find that the selective measurements on the data buses can protect quantum information of two superconducting qubits and force information to flow back to the superconducting qubits from the data buses by a witness of the trace distance.

Journal of the Optical Society of America BJul 24, 20136 citations

Quantum measurement in superconducting qubits

Michael Hatridge

Bulletin of the American Physical SocietyMar 7, 20190 citations

Quantum Zeno effect with a superconducting qubit

Yuichiro Matsuzaki, Shiro Saito, Kosuke Kakuyanagi +1 more

Detailed schemes are investigated for experimental verification of Quantum Zeno effect with a superconducting qubit. A superconducting qubit is affected by a dephasing noise whose spectrum is $1/f$ and so the decay process of a superconducting qubit shows a naturally nonexponential behavior due to an infinite correlation time of $1/f$ noise. Since projective measurements can easily influence the decay dynamics having such nonexponential feature, a superconducting qubit is a promising system to observe quantum Zeno effect. We have studied how a sequence of projective measurements can change the dephasing process and also we have suggested experimental ways to observe quantum Zeno effect with a superconducting qubit. It would be possible to demonstrate our prediction in the current technology.Detailed schemes are investigated for experimental verification of Quantum Zeno effect with a superconducting qubit. A superconducting qubit is affected by a dephasing noise whose spectrum is $1/f$ and so the decay process of a superconducting qubit shows a naturally nonexponential behavior due to an infinite correlation time of $1/f$ noise. Since projective measurements can easily influence the decay dynamics having such nonexponential feature, a superconducting qubit is a promising system to observe quantum Zeno effect. We have studied how a sequence of projective measurements can change the dephasing process and also we have suggested experimental ways to observe quantum Zeno effect with a superconducting qubit. It would be possible to demonstrate our prediction in the current technology.

arXiv:1006.2133Physical Review BNov 23, 201034 citations

Nonlinearities in the quantum measurement process of superconducting qubits

I. Serban

Jan 1, 20081 citation

Fast Microwave-free State Preparation and Measurement of Superconducting Qubits

R. Abraham, F. Amet, P. Anderson +212 more

Fast, high-fidelity, scalable state preparation and measurement is critical to the realization of a quantum computing system. The state-of-the-art methods for preparation and readout of superconducting qubits require finely tuned microwave signals and ~100 ns of measurement time, which are major obstacles to the scalability and performance of superconducting quantum computers. Here, we have demonstrated novel, microwave-free methods for both preparation and readout of superconducting qubits with >99% fidelity in only 10 ns for either operation while maintaining qubit coherence. This technology is compatible with scalable superconducting digital control systems, and using quantum flux parametrons for amplification, we demonstrated full quantum-to-digital conversion in only 15 ns, which is an order of magnitude faster than state-of-the-art microwave-based techniques.Fast, high-fidelity, scalable state preparation and measurement is critical to the realization of a quantum computing system. The state-of-the-art methods for preparation and readout of superconducting qubits require finely tuned microwave signals and ~100 ns of measurement time, which are major obstacles to the scalability and performance of superconducting quantum computers. Here, we have demonstrated novel, microwave-free methods for both preparation and readout of superconducting qubits with >99% fidelity in only 10 ns for either operation while maintaining qubit coherence. This technology is compatible with scalable superconducting digital control systems, and using quantum flux parametrons for amplification, we demonstrated full quantum-to-digital conversion in only 15 ns, which is an order of magnitude faster than state-of-the-art microwave-based techniques.

quant-pharXiv:2609.01334Sep 2, 20260 citations

Efficient and Low-Backaction Quantum Measurement Using a Chip-Scale Detector

Eric I. Rosenthal, C. M. F. Schneider, M. Malnou +13 more

Superconducting qubits are a leading platform for scalable quantum computing and quantum error correction. One feature of this platform is the ability to perform projective measurements orders of magnitude more quickly than qubit decoherence times. Such measurements are enabled by the use of quantum-limited parametric amplifiers in conjunction with ferrite circulators-magnetic devices which provide isolation from noise and decoherence due to amplifier backaction. Because these nonreciprocal elements have limited performance and are not easily integrated on chip, it has been a long-standing goal to replace them with a scalable alternative. Here, we demonstrate a solution to this problem by using a superconducting switch to control the coupling between a qubit and amplifier. Doing so, we measure a transmon qubit using a single, chip-scale device to provide both parametric amplification and isolation from the bulk of amplifier backaction. This measurement is also fast, high fidelity, and has 70% efficiency, comparable to the best that has been reported in any superconducting qubit measurement. As such, this work constitutes a high-quality platform for the scalable measurement of superconducting qubits.Superconducting qubits are a leading platform for scalable quantum computing and quantum error correction. One feature of this platform is the ability to perform projective measurements orders of magnitude more quickly than qubit decoherence times. Such measurements are enabled by the use of quantum-limited parametric amplifiers in conjunction with ferrite circulators-magnetic devices which provide isolation from noise and decoherence due to amplifier backaction. Because these nonreciprocal elements have limited performance and are not easily integrated on chip, it has been a long-standing goal to replace them with a scalable alternative. Here, we demonstrate a solution to this problem by using a superconducting switch to control the coupling between a qubit and amplifier. Doing so, we measure a transmon qubit using a single, chip-scale device to provide both parametric amplification and isolation from the bulk of amplifier backaction. This measurement is also fast, high fidelity, and has 70% efficiency, comparable to the best that has been reported in any superconducting qubit measurement. As such, this work constitutes a high-quality platform for the scalable measurement of superconducting qubits.

arXiv:2008.03805Physical Review LettersMar 3, 202132 citations

Detailed schemes are investigated for experimental verification of Quantum Zeno effect with a superconducting qubit. A superconducting qubit is affected by a dephasing noise whose spectrum is

1/f

and so the decay process of a superconducting qubit shows a naturally nonexponential behavior due to an infinite correlation time of

1/f

noise. Since projective measurements can easily influence the decay dynamics having such nonexponential feature, a superconducting qubit is a promising system to observe quantum Zeno effect. We have studied how a sequence of projective measurements can change the dephasing process and also we have suggested experimental ways to observe quantum Zeno effect with a superconducting qubit. It would be possible to demonstrate our prediction in the current technology.