52 research outputs found
Robust Entanglement through Macroscopic Quantum Jumps
We propose an entanglement generation scheme that requires neither the
coherent evolution of a quantum system nor the detection of single photons.
Instead, the desired state is heralded by a {\em macroscopic} quantum jump.
Macroscopic quantum jumps manifest themselves as a random telegraph signal with
long intervals of intense fluorescence (light periods) interrupted by the
complete absence of photons (dark periods). Here we show that a system of two
atoms trapped inside an optical cavity can be designed such that a dark period
prepares the atoms in a maximally entangled ground state. Achieving fidelities
above 0.9 is possible even when the single-atom cooperativity parameter C is as
low as 10 and when using a photon detector with an efficiency as low as eta =
0.2.Comment: 5 pages, 4 figures, more detailed discussion of underlying physical
effect, references update
Nanoparticle detection in an open-access silicon microcavity
We report on the detection of free nanoparticles in a micromachined,
open-access Fabry-P\'erot microcavity. With a mirror separation of m,
a radius of curvature of mm, and a beam waist of m, the mode
volume of our symmetric infrared cavity is smaller than pL. The small
beam waist, together with a finesse exceeding 34,000, enables the detection of
nano-scale dielectric particles in high vacuum. This device allows monitoring
of the motion of individual nm radius silica nanospheres in real time.
We observe strong coupling between the particles and the cavity field, a
precondition for optomechanical control. We discuss the prospects for optical
cooling and detection of dielectric particles smaller than nm in radius
and amu in mass.Comment: 4 pages, 3 figure
A three-dimensional electrostatic actuator with a locking mechanism for a new generation of atom chips
A micromachined three-dimensional electrostatic actuator that is optimized for aligning and tuning optical microcavities on atom chips is presented. The design of the 3D actuator is outlined in detail, and its characteristics are verified by analytical calculations and finite element modelling. Furthermore, the fabrication process of the actuation device is described and preliminary fabrication results are shown. The actuation in the chip plane which is used for mirror positioning has a working envelope of 17.5 ?m. The design incorporates a unique locking mechanism which allows the out-of-plane actuation that is used for cavity tuning to be carried out once the in-plane actuation is completed. A maximum translation of 7 ?m can be achieved in the out-of-plane direction
Nuclear Spin Quantum Memory in Silicon Carbide
Transition metal (TM) defects in silicon carbide (SiC) are a promising
platform for applications in quantum technology. Some TM defects, e.g.
vanadium, emit in one of the telecom bands, but the large ground state
hyperfine manifold poses a problem for applications which require pure quantum
states. We develop a driven, dissipative protocol to polarize the nuclear spin,
based on a rigorous theoretical model of the defect. We further show that
nuclear-spin polarization enables the use of well-known methods for
initialization and long-time coherent storage of quantum states. The proposed
nuclear-spin preparation protocol thus marks the first step towards an
all-optically controlled integrated platform for quantum technology with TM
defects in SiC.Comment: 12 Pages, 5 figure
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