Optimizing one-axis twists for variational Bayesian quantum metrology
May 15, 2024
Many quantum sensing technologies, such as magnetometers, measure a small rotation angle. Quantum mechanics places a fundamental limit on the quality of this measurement. Reaching this fundamental limit requires using carefully designed interactions between the sensor particles to create entanglement. It was recently found that these interactions can even facilitate a measurement that reaches this limit for both large and small angles so less information about the angle is needed ahead of time. Building on previous strategies, Tyler Thurtell and Akimasa Miyake reduced the number of interactions required and found that these strategies remain useful in the current noisy intermediate scale quantum (NISQ) era.
Prior work considered a type of entangling interaction called a one-axis twist and focused on strategies symmetric under 180° rotations about a particular axis. Thurtell and Miyake considered strategies without this symmetry. This removed any restriction on the types of one-axis twist used and led to a reduction in the number of twists required. The strategies using only a few twists outperform strategies with no entanglement even if the twists are not implemented perfectly or the rotation is noisy. Finally, they studied how the measurement quality depends on the number of particles in the sensor.
See the publication at https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.6.023179
