Atom Computing, a Boulder-based company, has developed a scalable, high-fidelity method for midcircuit measurement in quantum computing. The team used a single-species tweezer array of neutral 171Yb atoms to perform nondestructive state-selective and site-selective detection. This allows a subset of qubits to be measured while causing only percent-level errors on the remaining qubits. The technique also demonstrated the ability to reuse ancilla qubits and perform conditional refilling of ancilla sites to correct for occasional atom loss while maintaining the coherence of data qubits. M. A. Norcia and B. J. Bloom led the research.
“Measurement-based quantum error correction relies on the ability to determine the state of a subset of qubits (ancillas) within a processor without revealing or disturbing the state of the remaining qubits. Among neutral-atom-based platforms, a scalable, high-fidelity approach to midcircuit measurement that retains the ancilla qubits in a state suitable for future operations has not yet been demonstrated.”
M. A. Norcia et al.
Atom Computing: Midcircuit Qubit Measurement and Rearrangement in Atomic Array
In quantum computing, measuring and rearranging qubits within a processor is crucial. This process, known as midcircuit measurement, allows for the correction of quantum errors and the preservation of the state of the remaining qubits. This article discusses a recent study demonstrating a scalable, high-fidelity approach to midcircuit measurement in a single-species tweezer array of neutral 171Yb atoms.
Quantum Error Correction and Midcircuit Measurement
Quantum error correction is a process that relies on the ability to determine the state of a subset of qubits, known as ancillas, within a processor. This is done without revealing or disturbing the state of the remaining qubits. Midcircuit measurement is a promising approach to quantum error correction. It involves repeated measurement of the ancilla qubits, which helps to remove entropy from the processor faster than it can enter.
Challenges in Quantum Processors
In quantum processors based on individually controlled atoms, measurement is typically performed by collecting light resonantly scattered by the atoms from a laser beam. However, performing measurements on a subset of atoms without introducing errors on others is difficult. This is due to the challenges of directing laser light solely on a subset of closely spaced atoms and the potential for photons scattered by the atoms being measured to be reabsorbed by others.
A New Approach to Midcircuit Measurement
The study from Atom Computing presents a scalable and high-fidelity method for midcircuit measurement in a single-species tweezer array of neutral 171Yb atoms. This approach is based on imaging light scattered from a narrow-linewidth transition, which, when combined with Zeeman shifts and light shifts, allows for highly state-selective and site-selective imaging. This enables high-fidelity readout of arbitrarily chosen ancilla qubits within the array, while imparting only percent-level loss of contrast on non-measured qubits.
Conditional Operations and Future Applications
As a demonstration of how this technique can be used for conditional branching to correct for errors, the researchers performed optical pumping and repeated cycles of imaging on the ancilla qubits, while maintaining the coherence of data qubits. They also demonstrated loading of a magneto-optical trap with a minimal degree of qubit decoherence. This suggests potential for continuous operation beyond the lifetime of an individual atom within a tweezer, opening up new possibilities for the future of quantum computing.
“In this work, we perform imaging using a narrow-linewidth transition in an array of tweezer-confined 171Yb atoms to demonstrate nondestructive state-selective and site-selective detection. By applying site-specific light shifts, selected atoms within the array can be hidden from imaging light, which allows a subset of qubits to be measured while causing only percent-level errors on the remaining qubits.” – M. A. Norcia et al.
“Useful error-corrected quantum computers must remove entropy from the processor faster than it can enter. At the physical qubit level, entropy enters through errors due either to the interaction of the qubit with its environment or to imperfect control of a qubit.” – M. A. Norcia et al.
“In this work, we present a scalable and high-fidelity method for midcircuit measurement in a single-species tweezer array of neutral 171Yb atoms. Our approach is based on imaging light scattered from a narrow-linewidth transition, which, when combined with Zeeman shifts and light shifts, allows us to perform highly state-selective and site-selective imaging.” – M. A. Norcia et al.
“The ability to determine the quantum state of an atom without it being lost from the trap is a useful capability for midcircuit measurements. In many neutral-atom systems, the state of single atoms is determined by introducing state-selective loss followed by state-independent imaging of the remaining atoms.” – M. A. Norcia et al.
Summary
Scientists from Atom Computing have developed a scalable, high-fidelity method for midcircuit measurement in quantum computing using a single-species tweezer array of neutral 171Yb atoms. This approach allows for high-fidelity readout of selected qubits within the array, while maintaining the coherence of data qubits, and could be used for conditional branching to correct for errors.
- Atom Computing, a quantum computing company, has developed a scalable, high-fidelity method for midcircuit measurement in a single-species tweezer array of neutral 171Yb atoms.
- The method involves imaging light scattered from a narrow-linewidth transition, combined with Zeeman shifts, allowing for highly state-selective and site-selective imaging.
- This enables high-fidelity readout of arbitrarily chosen ancilla qubits within the array, while imparting only percent-level loss of contrast on non-measured qubits.
- The approach has a high probability of retaining the ancilla qubits in a suitable condition for further use.
- The team demonstrated how the technique can be used for conditional branching to correct for errors, as well as the ability to perform reset and repeated measurements of the same ancilla qubits.
- The research was led by M. A. Norcia, W. B. Cairncross, K. Barnes, P. Battaglino, A. Brown, M. O. Brown, K. Cassella, C.-A. Chen, R. Coxe, D. Crow, J. Epstein, C. Griger, A. M. W. Jones, H. Kim, J. M. Kindem, J. King, S. S. Kondov, K. Kotru, J. Lauigan, M. Li, M. Lu, E. Megidish, J. Marjanovic, M. McDonald, T. Mittiga, J. A. Muniz, S. Narayanaswami, C. Nishiguchi, R. Notermans, T. Paule, K. A. Pawlak, L. S. Peng, A. Ryou, A. Smull, D. Stack, M. Stone, A. Sucich, M. Urbanek, R. J. M. van de Veerdonk, Z. Vendeiro, T. Wilkason, T.-Y. Wu, X. Xie, X. Zhang, and B. J. Bloom.