Quantum computation speedup limits from quantum metrological precision bounds

Quantum speedup in stoquastic adiabatic quantum computation

Quantum computation provides exponential speedup for solving certain mathematical problems against classical computers. Motivated by current rapid experimental progress on quantum computing devices, various models of quantum computation have been investigated to show quantum computational supremacy. At a commercial side, quantum annealing machine realizes the quantum Ising model with a transver...

Quantum metrological limits via a variational approach.

The minimum achievable statistical uncertainty in the estimation of physical parameters is determined by the quantum Fisher information. Its computation for noisy systems is still a challenging problem. Using a variational approach, we present an equation for obtaining the quantum Fisher information, which has an explicit dependence on the mathematical description of the noise. This method is a...

Quantum speedup by quantum annealing.

We study the glued-trees problem from A. M. Childs, R. Cleve, E. Deotto, E. Farhi, S. Gutmann, and D. Spielman, in Proceedings of the 35th Annual ACM Symposium on Theory of Computing (ACM, San Diego, CA, 2003), p. 59. in the adiabatic model of quantum computing and provide an annealing schedule to solve an oracular problem exponentially faster than classically possible. The Hamiltonians involve...

True precision limits in quantum metrology

Quantum mechanics provides insight into fundamental limits on the achievable measurement precision that cannot be beaten irrespectively of the extent of any improvements in measurement technology. The best known example is that of the optical phase measurement where difference of phase delays φ in the arms of interferometer in the absence of decoherence can only be measured up to a precision kn...

Precision bounds for noisy nonlinear quantum metrology