Physics Department News
Dimensionless ratios of physical properties can characterize low-temperature phases in a wide variety of materials. As such, the Wilson ratio (WR), the Kadowaki-Woods ratio, and the Wiedemann-Franz law capture essential features of Fermi liquids in metals, heavy fermions, etc. Here we prove that the phases of many-body interacting multicomponent quantum liquids in one dimension can be described by WRs based on the compressibility, susceptibility, and specific heat associated with each component. These WRs arise due to additivity rules within subsystems reminiscent of the rules for multiresistor networks in series and parallel—a novel and useful characteristic of multicomponent Tomonaga-Luttinger liquids independent of microscopic details of the systems.
Quantum imaging with Gaussian light
Today, a picture taken by a camera on a typical smartphone can consist of more than 10 million pixels. This is the reality of modern-day cameras and imaging. The ability of record millions of pixels simultaneously will therefore be expected to be a necessary part of any future imaging technology as a matter of course. And that includes quantum enhanced strategies. Measuring (or estimating) multiple parameters simultaneously, however, is one of the fundamental limitations of quantum mechanics. It is what sets quantum mechanics apart from classical physics. What then is the future of quantum enhanced imaging ?
The mystery of the missing tetraquark
The LHCb collaboration has searched for signals of a new particle, recently claimed by the D0 collaboration. Finding no signal, limits are set which are apparently at odds with the D0 claim.