4 research outputs found
Optimised control of Stark-shift-chirped rapid-adiabatic-passage in a lambda-type three-level system
Inhomogeneous broadening of energy levels is one of the principal limiting
factors for achieving "slow" or "stationary" light in solid state media by
means of electromagnetically induced transparency (EIT), a quantum version of
stimulated Raman adiabatic passage (STIRAP). Stark-shift-chirped
rapid-adiabatic-passage (SCRAP) has been shown to be far less sensitive to
inhomogeneous broadening than STIRAP, a population transfer technique to which
it is closely related. We further optimise the pulses used in SCRAP to be even
less sensitive to inhomogeneous broadening in a lambda-type three-level system.
The optimised pulses perform at a higher fidelity than the standard gaussian
pulses for a wide range of detunings (i.e. large inhomogeneous broadening).Comment: 6 pages, 6 figures, 1 tabl
Giant Kerr nonlinearities in Circuit-QED
The very small size of optical nonlinearities places wide ranging
restrictions on the types of novel physics one can explore. For an ensemble of
multi-level systems one can synthesize a large effective optical nonlinearity
using quantum coherence effects but such non-linearities are technically
extremely challenging to demonstrate at the single atom level. In this work we
describe how a single artificial multi-level Cooper Pair Box molecule,
interacting with a superconducting microwave coplanar waveguide resonator, when
suitably driven, can generate extremely large optical nonlinearities at
microwave frequencies, with no associated absorption. We describe how the giant
self-Kerr effect can be detected by measuring the second-order correlation
function and quadrature squeezing spectrum.Comment: 4 pages, 4 figures, 1 table; version accepted by PRL edito
Perfect mirror transport protocol with higher dimensional quantum chains
A globally controlled scheme for quantum transport is proposed. The scheme
works on a 1D chain of nearest neighbor coupled systems of qudits (finite
dimension), or qunats (continuous variable), taking any arbitrary initial
quantum state of the chain and producing a final quantum state which is
perfectly spatially mirrored about the mid-point of the chain. As a particular
novel application, the method can be used to transport continuous variable (CV)
quantum states. A physical realization is proposed where it is shown how the
quantum states of the microwave fields held in a chain of driven
superconducting coplanar waveguides can experience quantum mirror transport
when coupled by switchable Cooper Pair Boxes.Comment: Published version; 4 pages, 4 Figure
Memory-enhanced noiseless cross-phase modulation
Large nonlinearity at the single-photon level can pave the way for the implementation of universal quantum gates. However, realizing large and noiseless nonlinearity at such low light levels has been a great challenge for scientists in the past decade. Here, we propose a scheme that enables substantial nonlinear interaction between two light fields that are both stored in an atomic memory. Semiclassical and quantum simulations demonstrate the feasibility of achieving large cross-phase modulation (XPM) down to the single-photon level. The proposed scheme can be used to implement parity gates from which CNOT gates can be constructed. Furthermore, we present a proof of principle experimental demonstration of XPM between two optical pulses: one stored and one freely propagating through the memory medium.5 page(s