Uhlmann phase of coherent states and the Uhlmann-Berry correspondence

A Measurement Protocol for the Topological Uhlmann Phase

Topological insulators and superconductors at finite temperature can be characterised by the topological Uhlmann phase. However, the direct experimental measurement in condensed matter systems has remained elusive. We explicitly demonstrate that the topological Uhlmann phase can be measured with the help of ancilla states in systems of entangled qubits that simulate a topological insulator. We ...

Macroscopic distinguishability between quantum states defining different phases of matter: fidelity and the Uhlmann geometric phase.

We study the fidelity approach to quantum phase transitions (QPTs) and apply it to general thermal phase transitions (PTs). We analyze two particular cases: The Stoner-Hubbard itinerant electron model of magnetism and the BCS theory of superconductivity. In both cases we show that the sudden drop of the mixed state fidelity marks the line of the phase transition. We conduct a detailed analysis ...

Conference on Inverse Problems in Honor of Gunther Uhlmann

RIGIDITY OF BROKEN GEODESIC FLOW AND INVERSE PROBLEMS By YAROSLAV KURYLEV, MATTI LASSAS, and GUNTHER UHLMANN

Consider broken geodesics α([0, l]) on a compact Riemannian manifold (M, g) with boundary of dimension n ≥ 3. The broken geodesics are unions of two geodesics with the property that they have a common end point. Assume that for every broken geodesic α([0, l]) starting at and ending to the boundary ∂M we know the starting point and direction (α(0),α′(0)), the end point and direction (α(l),α′(l))...

An Inverse Source Problem in Optical Molecular Imaging Plamen Stefanov and Gunther Uhlmann

We study the direct and an inverse source problem for the radiative transfer equation arising in optical molecular imaging. We show that for generic absorption and scattering coefficients, the direct problem is well-posed and the inverse one is uniquely solvable, with a stability estimate.