FOUNDATIONS ................................................................................................................ 456 Signals and Noise, Detectability and Discriminability ............................................... 456 Noise from Classical Statistical Mechanics ............................................................... 459 Noise from Quantum Mechanics .........................

Tantalum oxide memristors can switch continuously from a low-conductance semiconducting to a high-conductance metallic state. At the boundary between these two regimes are quantized conductance states, which indicate the formation of a point contact within the oxide characterized by multistable conductance fluctuations and enlarged electronic noise. Here, we observe diverse conductance-dependen...

2 Aspice convexo nutantem pondere mundum terrasque tractusque maris caelumque profundum. Behold the world swaying her convex mass, lands and spaces of sea and depth of sky. This manuscript must be intended as an informal review of the research works carried out during three years of PhD. " Informal " in the sense that technical proofs are often omitted (they can be found in the papers) as one c...

A new technique for evaluating the performance of quantum signals observed in the presence of noise is described and evaluated. The quantum theory for detecting coherent-state signals has been developed previously; however, the quantum signal-plus-noise problem has received little attention due to its complexity. Here we develop a discrete approximation to the coherent-state representation of s...

Transmission of quantum entanglement will play a crucial role in future networks and longdistance quantum communications. Quantum Key Distribution, the working mechanism of quantum repeaters and the various quantum communication protocols are all based on quantum entanglement. On the other hand, quantum entanglement is extremely fragile and sensitive to the noise of the communication channel ov...

We report the noise characteristics of quantum point contacts between 100 Hz and 100 kHz at 4.2 K. The noise consists of a 111 component on top of a white background. The 1I/noise increases as the contact width decreases and shows peaks between the quantized resistance plateaus. The white noise background increases with current but is much lower than the fuB shot noise level, suggesting that sh...

Quantum annealing is a powerful alternative model of quantum computing, which can succeed in the presence environmental noise even without error correction. However, despite great effort, no conclusive demonstration speedup (relative to state art classical algorithms) has been shown for these systems, and rigorous theoretical proofs advantage (such as adiabatic formulation Grover's search probl...