Upcoming seminars

Given a system of massive quantum harmonic oscillators, how can we test whether their gravitational interaction is classical or quantum? Here we propose a general Gedankenexperiment to do so and benchmark it, i.e. we show how to determine the threshold beyond which one can claim that gravity behaves as a quantum interaction Hamiltonian instead of a classical field. The remarkable aspect of our approach is that it bypasses completely the problem of how a classical gravitational field may interact with the quantum oscillators.

Quantum technology is creating an increasing research activity in information theory, engineering, and physics. One example is the theory of quantum channels with input constraints. This line of research has seen new results in quantum communication theory and quantum dynamics, but its basic functional analysis is still unexplored. Here, we provide a version of Choquet’s theorem regarding constrained sets of states. The result simplifies the definitions of several characteristics of quantum information theory.

The standard operational framework of quantum theory is time-asymmetric. This asymmetry reflects the capabilities of ordinary agents, who are able to deterministically pre-select the states of quantum systems, but not to deterministically post-select the outcomes of quantum measurements. However, the fundamental dynamics of quantum particles is time-symmetric, and is compatible with a broader class of operations where pre-selections and post-selections are combined in general ways that do not presuppose a definite direction of time.

I’ll review what is the current state of quantum computing with superconducting qubits.​ ​I’ll explain several experiments from Google’s Quantum AI group, including an article published in Nature in 2019 in which we carried out a computational task on an experimental quantum processor vastly outperforming current supercomputers. I will conclude with various projections on the expected advances in quantum computing in the next ten years.