Strong micro-macro entanglement from a weak cross-Kerr nonlinearity

Abstract

We study the entanglement generated by a weak cross-Kerr nonlinearity between two initial coherent states, one of which has an amplitude close to the single-photon level, while the other one is macroscopic. We show that strong micro-macro entanglement is possible for weak phase shifts by choosing the amplitude of the macroscopic beam sufficiently large. We analyze the effects of loss and discuss possible experimental demonstrations of the micro-macro entanglement based on homodyne tomography and on a new entanglement witness

Creating cat states in one-dimensional quantum walks using delocalized initial states

“…Due to their macroscopic nature, cat states play an important role in fundamental tests of quantum theory and precision measurements [5][6][7][8]. Numerous attempts are being made to prepare cat states in various physical systems [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27].…”

Nonclassical statistics from a polaritonic Josephson junction

“…The scheme relies on a classical to quantum transition in a nonlinear medium, where a macroscopically occupied mode is periodically coupled to a weakly occupied state [35,36]. One can therefore take advantage of exciton-polariton Josephson oscillations, already reported twice [37,38] in the NBEC regime.…”

Multivalley engineering in semiconductor microcavities

“…The first one ( α ) stands for the interaction of EPs located within the same minimum, while the second term (4 α ) accounts for the cross-interactions between the minima which fulfills the energy momentum conservation by exchange of the wave vector + k  → − k and no energy change (see Supplementary for details). Physically, the latter term corresponds to the cross-Kerr interaction which is known to induce two-mode squeezing52, and therefore continuous variable entanglement is expected to occur in reciprocal space.…”