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arXiv · 1509.00860

Comparing and combining measurement-based and driven-dissipative entanglement stabilization

Yehan Liu·Shyam Shankar·Nissim Ofek·Michael Hatridge·Anirudh Narla·Katrina Sliwa·Luigi Frunzio·Robert J. Schoelkopf·Michel H. Devoret
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Abstract

We demonstrate and contrast two approaches to the stabilization of qubit entanglement by feedback. Our demonstration is built on a feedback platform consisting of two superconducting qubits coupled to a cavity which are measured by a nearly-quantum-limited measurement chain and controlled by high-speed classical logic circuits. This platform is used to stabilize entanglement by two nominally distinct schemes: a "passive" reservoir engineering method and an "active" correction based on conditional parity measurements. In view of the instrumental roles that these two feedback paradigms play in quantum error-correction and quantum control, we directly compare them on the same experimental setup. Further, we show that a second layer of feedback can be added to each of these schemes, which heralds the presence of a high-fidelity entangled state in realtime. This "nested" feedback brings about a marked entanglement fidelity improvement without sacrificing success probability.

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Yehan Liu, Shyam Shankar, Nissim Ofek, Michael Hatridge, Anirudh Narla, Katrina Sliwa, Luigi Frunzio, Robert J. Schoelkopf, Michel H. Devoret. 2015-09-02. Comparing and combining measurement-based and driven-dissipative entanglement stabilization. https://doi.org/10.1103/physrevx.6.011022

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