arXiv subjects

Keith Kastella

Publications and source records attributed to Keith Kastella.

2 recordsLinked to original sources

arXiv2010

Signal Enhancement and Background Suppression Using Interference and Entanglement

We describe two-photon absorption processes excited by entangled pairs, but not by non-entangled pairs of the same energy and polarization. Photon states are selected for destructive interference in the non-entangled process between different sequences of absorption via multiple intermediate states. A non-zero entangled absorption cross section is obtained by varying the entanglement time and pair delay parameters. Detailed energy and polarization requirements are derived for Rb 5S1/2 --> 5D3/2 transitions. Applications to Quantum Steganography and Quantum Key Distribution are discussed.

quant-ph↗

arXiv2001

Structured quantum search in NP-complete problems using the cumulative density of states

In the multitarget Grover algorithm, we are given an unstructured N-element list of objects S_i containing a T-element subset tau and function f, called an oracle, such that f(S_i)=1 if S_i is in tau, otherwise f(S_i) = 0. By using quantum parallelism, an element of tau can be retrieved in O(sqrt(N/T)) steps, compared to O(N/T) for any classical algorithm. It is shown here that in combinatorial optimization problems with N=4^M, the density of states can be used in conjunction with the multitarget Grover algorithm to construct a sequence of oracles that structure the search so that the optimum state is obtained with certainty in O(log(N)) steps.

quant-ph↗