Everyone is welcome to attend online the QuSoft seminar, this week with Xiaoliang Qi (Stanford) on 'Quantum Algorithmic Measurement'.
Abstract:
Can quantum computational tools enhance the precision and efficiency of physical experiments? Promising examples are known, but a systematic treatment and comprehensive framework are missing. We introduce Quantum Algorithmic Measurements (QUALMs) to enable the study of quantum measurements and experiments from the perspective of computational complexity and communication complexity. The measurement process is described, in its utmost generality, by a many-round quantum interaction
protocol between the experimental system and a full-fledged quantum computer. The QUALM complexity is quantified by the number of elementary operations performed by the quantum computer, including its coupling to the experimental system. We study how the QUALM complexity depends on the type of allowed access the quantum computer has to the experimental system: coherent, incoherent, etc. We provide a new example of a measurement "task", which can be motivated by the study of Floquet
systems, for which the coherent access QUALM complexity is exponentially better than the incoherent one, even if the latter is adaptive; this implies that using entanglement between different systems in experiments, as well as coherence between probes to the physical system at different times, may lead to exponential savings in resources. We extend our results to derive a similar exponential advantage for another physically motivated measurement task which determines the symmetry class of the time evolution operator for a quantum many-body system.
Please contact Subharee Patro or Jop Briet for the zoom link.
