Tomorrow we will hear from two speakers, Martina Niggli and Aaron Leu, on their master thesis and semester project, respectively. See below for the titles and abstracts. We start at the usual time, 2pm on zoom: https://ethz.zoom.us/j/362994444.

Best,

Joe

Speaker: Martina Niggli

Title: Quantum State Discrimination: Global Measurements vs. One-way LOCC

Abstract: The task of quantum state discrimination is considered in two different setups: First, we analyze the setup where one party is provided with a quantum system that was prepared in one of two states at random. We review the optimal measurement to distinguish between the two states, the Helstrom measurement, and we provide a theorem that characterizes the set of all optimal measurements. Second, we look at the setup where each of two spatially separated parties is provided with one part of a composite system, which was prepared in one of two possible states. The two parties are restricted to one-way LOCC strategies in order to determine the state of their shared system. We review a known optimal strategy for pure states, and we provide a new strategy that can be applied for arbitrary states. The success probability of this new strategy is compared to that of a global Helstrom measurement for different types of states, and we characterize conditions under which the new strategy performs optimally.

Speaker: Aaron Leu

Title: Information-to-work conversion

Abstract: 

As stated in the formulation of the second law of thermodynamics by Kelvin and Plank, it is impossible to convert heat directly into work. However, it has been known for more than 50 years that one can use information to extract work out of a heat reservoir, but it has only been implemented experimentally a few years ago. In most of the experiments they were able to measure or calculate the extracted work, but they did not describe information flows at all. The characterisation of the information was hardly possible, because feedback control was required. In order to describe the whole system with all its energy and information flows, we need a closed autonomous quantum system. A broad variety of Quantum technologies provide us with a lot of different tools, advantages and disadvantages. Our goal is to find a platform to implement an information-to-work protocol, which fulfills our requirements and is experimentally feasible. We restrict ourselves to quantum technologies that are available at the ETH, such that we can start a collaboration for an experimental realization in the future.