Dear quanta,

We will have no group meeting tomorrow. (Our next meeting will be Fri, Nov 9, and John Napp is speaking.)

Instead, there are two talks that should interest many of us.

1.

title: Quantum lightning never strikes the same state twice

Friday, November 2, 2018 - 10:30am to 12:00pm
Location: 32-G882
Speaker: Mark Zhandry, Princeton

Abstract: Quantum no-cloning states that it is physically impossible to clone a quantum state.  No-cloning is a central to the study of quantum cryptography, where it allows for objects such as physically unforgeable currency.  In this work, I study two strong variants of no-cloning: (1) public key quantum money, where the would-be cloner is given a verification oracle for checking if it successfully cloned; and (2) quantum lightning, where the cloner even knows all the details of how the initial state was constructed.  I then give a variety of results for public key quantum money and quantum lightning, yielding new constructions and interesting connections to other areas of cryptography.

2.

title:  Compass Codes

Fri, Nov 2 - 1:30pm-2:30pm

speaker: Ken Brown (Duke)

abstract:
The compass model of condensed-matter physics directly inspired the Bacon-Shor subsystem code, but both the Shor code and the rotated surface code can be considered as alternate choices for fixing gauge operators. I will discuss our work exploring the space of compass codes on LxL lattices and potential advantages over the surface codes for errors that are anisotropic or inhomogeneous in space. I will then focus on distance 3 versions of the compass code and describe their possible implementation with trapped atomic ions. This will include a discussion of stabilizer slicing for correcting systematic errors during syndrome extraction.