EPR and Bell’s theorem, and quantum algorithms

EPR showed that quantum mechanics is not a local deterministic theory and on this account they argued that it is incomplete. Quantum mechanics predicts correlations over time-like separations. The suggested resolution in terms of local hidden variables is presented. Bell’s analysis leading to experimental tests is described. The experiment of Aspect, Grangier and Roger vindicating quantum mechanics is described. More refined experiments, avoiding conceivable biases, confirm this result. Then computing based on quantum principles is discussed. Bits with two states in a register would be replaced by qubits with values represented by points on the Bloch sphere. Basic gates are presented. Shor’s algorithm to decompose products of primes is described and a gate structure presented to implement it. Implementation would undermine current encryption methods. Quantum cryptography is described using the BB84 protocol. The no-cloning theorem protects this absolutely against attempts to intercept the encryption data.