Colloquium: Dr. Aaron Friedman | CU Boulder

ABSTRACT: Measurements are a fundamental part of quantum theory. In addition to establishing some of the first historic departures of the theory from classical physics, they are also how we learn about quantum states, operations, and even computations! While we usually think of measurements as the final step of a quantum computation or operation, in this talk, I will show how they can be used to prepare quantum systems and complete operations and computations more efficiently on the noisy intermediate-scale quantum (NISQ) devices currently available. I will first briefly summarize measurements and their unitary description acting on the system and detector. Next, I will discuss how we used this description to reveal fundamental limits on the speed of quantum information and entanglement generation in measurement-based protocols. I will consider quantum teleportation as a concrete example, and discuss how we used the foregoing ideas to prove its equivalence to preparing a particular quantum phase of matter. I will conclude by discussing my planned applications for these ideas, including revealing new resource tradeoffs, developing and optimizing quantum protocols (for quantum error correction, state preparation, etc.), and tailoring protocols to particular NISQ hardware.