We study the formation of an exciton condensate in GaAs coupled quantum wells at low temperatures. We show that the condensate consists of dark excitons, and extends over hundreds of {mu}m, limited only by the boundaries of the mesa. We find that the
condensate density is determined by spin flipping collisions among the condensate excitons and with the thermal bath. We show that these processes, which convert dark excitons to bright, evaporatively cool the system to temperatures that are much lower than the bath temperature. We present a rate equations model, which explains the temperature and power dependence of the exciton density, and in particular - the large density buildup at low temperatures. We confirm the validity of the model by reproducing the unique behavior observed when a magnetic field is applied in a direction parallel to the layers.
Randomization procedures are used in legal and statistical applications, aiming to shield important decisions from spurious influences. This article gives an intuitive introduction to randomization and examines some intended consequences of its use r
elated to truthful statistical inference and fair legal judgment. This article also presents an open-code Java implementation for a cryptographically secure, statistically reliable, transparent, traceable, and fully auditable randomization tool.
We present measurements of superconducting flux qubits embedded in a three dimensional copper cavity. The qubits are fabricated on a sapphire substrate and are measured by coupling them inductively to an on-chip superconducting resonator located in t
he middle of the cavity. At their flux-insensitive point, all measured qubits reach an intrinsic energy relaxation time in the 6-20 microseconds range and a pure dephasing time comprised between 3 and 10 microseconds. This significant improvement over previous works opens the way to the coherent coupling of a flux-qubit to individual spins.
