An international research team from the University of São Paulo and the Beijing Institute of Technology has proposed a new method for reading quantum information. The approach utilizes Andreev qubits, which are based on superconducting materials and indium arsenide nanowires.
Unlike traditional methods that require auxiliary qubits to prevent state collapse, this system monitors the current signals generated by the qubit itself. The qubit is placed in a closed superconducting circuit where supercurrents oscillate periodically due to quantum interference between states.
Researchers use a SQUID (Superconducting Quantum Interference Device) to detect these weak magnetic field changes without significantly disturbing the qubit. The current's constant value, oscillation amplitude, and timing allow for the reconstruction of the original quantum state.
This technique enables continuous tracking of qubit evolution without the need for re-initialization after each measurement. Simulations accounting for noise and feedback demonstrated measurement accuracies of 99.52%, 99.81%, and 99.85%, meeting current quantum error correction standards.
The findings were published in Physical Review B. The team notes that the required SQUID technology is already mature, meaning the implementation relies on existing materials and manufacturing capabilities rather than future breakthroughs.
