Almost all quantum states have nonclassical correlations

Almost quantum correlations.

Quantum theory is not only successfully tested in laboratories every day but also constitutes a robust theoretical framework: small variations usually lead to implausible consequences, such as faster-than-light communication. It has even been argued that quantum theory may be special among possible theories. Here we report that, at the level of correlations among different systems, quantum theo...

Almost all Pauli Channels have non-zero quantum capacities

Quantum transmission rate may be improved by using input of entangled state instead of product state for Pauli channel. Using GHZ state as input for the depolarizing channel (a special Pauli channel), the channel fidelity of non-zero quantum capacity was improved from > 0.81071 to > 0.80944. We will introduce orthogonal and complete code basis to evaluate the coherent information per channel us...

Exact quantum algorithms have advantage for almost all Boolean functions

It has been proved that almost all n-bit Boolean functions have exact classical query complexity n. However, the situation seemed to be very different when we deal with exact quantum query complexity. In this paper, we prove that almost all n-bit Boolean functions can be computed by an exact quantum algorithm with less than n queries. More exactly, we prove that ANDn is the only n-bit Boolean f...

Characterizing nonclassical correlations via local quantum uncertainty.

Quantum mechanics predicts that measurements of incompatible observables carry a minimum uncertainty which is independent of technical deficiencies of the measurement apparatus or incomplete knowledge of the state of the system. Nothing yet seems to prevent a single physical quantity, such as one spin component, from being measured with arbitrary precision. Here, we show that an intrinsic quant...

Highly Nonclassical Quantum States and Environment Induced Decoherence Highly Nonclassical Quantum States and Environment Induced Decoherence