Quantum Cryptography with Correlated Twin Laser Beams

Abstract

The data transmission protocol, based on the use of a strongly correlated pair of laser beams, is proposed. The properties of the corresponding states are described in detail. The protocol is based on the strong correlation of photon numbers in both beams in each measurement. The protocol stability against the interception attempts is analyzed.

Heisenberg-limited interferometry with pair coherent states and parity measurements

“…( 14) for the coefficients of TMSVS is equivalent to the product state a b ξ ξ − can be seen by expanding out the latter using Eqs. (18). Of course, the modes become re-entangled by the action of the second beam splitter.…”

“…The PCS were first discussed in the quantum optics literature by Agarwal [13] and it has recently been shown theoretically that such states could be produced by non-degenerate parametric oscillators [14]. The states have been discussed with many applications in mind, such as violations of EPR-Bell-type inequalities [15], and continuous variable quantum information processing such as quantum teleportation [16], quantum communication [17], and quantum cryptography [18] ϕ ∆ = For the smaller ϕ we have sensitivity essentially at the HL whereas even for the larger value, apart from the large deviations for certain average photon numbers, the phase uncertainty is still fairly close to the Heisenberg limit. The PCS appear to be more robust for parity based interferometry than do the two-mode squeezed vacuum states.…”

Large-alphabet quantum key distribution with two-mode coherently correlated beams

“…In this work we prove the effectiveness of the alphabet extension for the new multiphoton QKD protocol which was proposed recently [4,5] on the basis of the special beam states called two mode coherently correlated (TMCC). These states have the strong correlation between the photon numbers in each of the two spatially parted modes.…”

“…At the same time the TMCC states differ from the usual two-mode correlated coherent states, because the average for any of the linear in field observable (e.g. the vector-potential) is equal to zero for each of the TMCC modes [4]. Thus each of the modes is not coherent to itself, but as the square in field observables (e.g.…”

Pair-coherent states of the pseudoharmonic oscillator

“…In order to examine the temporal stability, we consider the whole Hamiltonian of two noninteracting parts, a and b, e.g. two laser beams that are propagating independently of each other, corresponding to the two modes of the two-mode coherently correlated states: H (ab) = H (a) + H (b) [12], with the whole energy E n + E n+q =hω(2n…”