Loophole-Free Bell Inequality Violation with Superconducting Circuits: Concepts*

Non-locality is an essential resource for protocols in device-independent quantum processing [1,2]. For the first time, we bring this capability to the platform of superconducting circuits, one of the main contenders for realizing quantum computer systems.

In this talk, we present the progress towards realizing the main building block of these protocols; a loophole-free Bell inequality violation with superconducting qubits.

In our discussion we focus on the key requirements for achieving this goal: separating two coherently connected superconducting qubits by a 30-meter-long cryogenic quantum microwave link [3], generating high-fidelity entanglement deterministically [4], and reading out the state of superconducting qubits with high fidelity on short time scales [5].

[1] R. Colbeck and R. Renner, Nature Physics 8 (2012)

[2] U. Vazirani et al., PRL 116, 089901 (2016)

[3] P. Magnard et al., PRL 125, 260502 (2020)

[4] P. Kurpiers et al., Nature 558, 264 (2018)

[5] T. Walter et al., Phys. Rev. Applied 7, 054020 (2017)