Single-qubit thermometry

Single-cell photoacoustic thermometry.

A novel photoacoustic thermometric method is presented for simultaneously imaging cells and sensing their temperature. With three-seconds-per-frame imaging speed, a temperature resolution of 0.2°C was achieved in a photo-thermal cell heating experiment. Compared to other approaches, the photoacoustic thermometric method has the advantage of not requiring custom-developed temperature-sensitive b...

Isolating a Single Qubit in a Multi Qubit System

Quantum computing, a whole new paradigm to computing, is based on using Quantum Mechanics for computation. The basic element in a quantum computer is a “qubit” which is a two-state physical system. Unlike a classical bit which can exist in one of two states, 0 or 1, a qubit can not only exist in its two basis states, but also in any linear combination of these states. A quantum computer compris...

Single-qubit optical quantum fingerprinting.

We analyze and demonstrate the feasibility and superiority of linear optical single-qubit fingerprinting over its classical counterpart. For one-qubit fingerprinting of two-bit messages, we prepare "tetrahedral" qubit states experimentally and show that they meet the requirements for quantum fingerprinting to exceed the classical capability. We prove that shared entanglement permits 100% reliab...

Optimal discrimination of single-qubit mixed states

Single Qubit Estimation from Repeated Unsharp Measurements

When estimating an unknown single pure qubit state, the optimum fidelity is 2/3. As it is well known, the value 2/3 can be achieved in one step, by a single ideal measurement of the polarization along a random direction. I analyze the opposite strategy which is the long sequence of unsharp polarization measurements. The evolution of the qubit under the influence of repeated measurements is quit...