Andreev qubit readout from dynamic interference supercurrent

Abstract

Nondemolition protocols use ancilla qubits to identify the fragile quantum state of a qubit without destroying its encoded information, thus playing a crucial role in nondestructive quantum measurements particularly relevant for quantum error correction. However, the multitude of ancilla preparations, information transfers, and ancilla measurements in these protocols create an intrinsic overhead for information processing. Here we consider an Andreev qubit defined in a quantum-dot Josephson junction and show that the macroscopic time-dependent oscillatory supercurrent arising from the quantum interference of the many-body eigenstates, can be used to probe the qubit itself-arbitrarily close to the nondestructive limit-under currently available experimental capabilities. This readout of arbitrary superposition states of Andreev qubits avoids ancillae altogether and significantly reduces experimental overhead as no repetitive qubit reinitialization is needed. Our prediction of an AC-like Josephson effect without an applied external voltage, which enables the nondestructive qubit readout, is a unique macroscopic manifestation of the microscopic dynamics of the Andreev quantum state. Our findings should have an unprecedented impact on advancing research and applications involving Andreev dots, thus positioning them as promising qubit contenders for quantum processing and technologies.

7 pages and 3 figures

References in corpus (31)

• High-fidelity projective readout of a solid-state spin quantum register
• Quantum Non-demolition Detection of Single Microwave Photons in a Circuit
• Quantum sensing with arbitrary frequency resolution
• Josephson ${\phi }_0$-junction in nanowire quantum dots
• Quantum non-demolition measurement of a superconducting two-level system
• Coherent manipulation of Andreev states in superconducting atomic contacts
• Exciting Andreev pairs in a superconducting atomic contact
• Coherent manipulation of an Andreev spin qubit
• Andreev Level Qubit
• Spin-orbit splitting of Andreev states revealed by microwave spectroscopy
• Andreev quantum dots for spin manipulation
• Fermion-parity anomaly of the critical supercurrent in the quantum spin-Hall effect
• Nontopological zero-bias peaks in full-shell nanowires induced by flux tunable Andreev states
• Phase signature of topological transition in Josephson Junctions
• Direct manipulation of a superconducting spin qubit strongly coupled to a transmon qubit
• Zero-field Topological Superconductivity in Ferromagnetic Hybrid Nanowires
• Continuous monitoring of a trapped, superconducting spin
• High-fidelity measurement of qubits encoded in multilevel superconducting circuits
• Nondestructive detection of photonic qubits
• Supercurrent Spectroscopy of Andreev States
• Observation of Josephson Harmonics in Tunnel Junctions
• Quantum nondemolition measurement of an electron spin qubit
• Non-destructive measurement of electron spins in a quantum dot
• Signatures of interactions in the Andreev spectrum of nanowire Josephson junctions
• Circuit-QED with phase-biased Josephson weak links
• Repetitive quantum non-demolition measurement and soft decoding of a silicon spin qubit
• Coupled superconducting spin qubits with spin-orbit interaction
• Long-lived Andreev states as evidence for protected hinge modes in a bismuth nanoring Josephson junction
• Fabry-Perot superconducting diode
• Quantum non-demolition measurements of moving target states
• Renormalized and iterative formalism of the Andreev levels within large multi-parametric space