19 research outputs found
EIT and diffusion of atomic coherence
We study experimentally the effect of diffusion of Rb atoms on
Electromagnetically Induced Transparency (EIT) in a buffer gas vapor cell. In
particular, we find that diffusion of atomic coherence in-and-out of the laser
beam plays a crucial role in determining the EIT resonance lineshape and the
stored light lifetime.Comment: 5 pages, 8 figure
Optical parametric oscillation with distributed feedback in cold atoms
There is currently a strong interest in mirrorless lasing systems, in which
the electromagnetic feedback is provided either by disorder (multiple
scattering in the gain medium) or by order (multiple Bragg reflection). These
mechanisms correspond, respectively, to random lasers and photonic crystal
lasers. The crossover regime between order and disorder, or correlated
disorder, has also been investigated with some success. Here, we report
one-dimensional photonic-crystal lasing (that is, distributed feedback lasing)
with a cold atom cloud that simultaneously provides both gain and feedback. The
atoms are trapped in a one-dimensional lattice, producing a density modulation
that creates a strong Bragg reflection with a small angle of incidence. Pumping
the atoms with auxiliary beams induces four-wave mixing, which provides
parametric gain. The combination of both ingredients generates a mirrorless
parametric oscillation with a conical output emission, the apex angle of which
is tunable with the lattice periodicity
Controlling photons using electromagnetically induced transparency
It is well known that a dielectric medium can be used to manipulate properties of light pulses. However, optical absorption limits the extent of possible control: this is especially important for weak light pulses. Absorption in an opaque medium can be eliminated via quantum mechanical interference, an effect known as electromagnetically induced transparency. Theoretical and experimental work has demonstrated that this phenomenon can be used to slow down light pulses dramatically, or even bring them to a complete halt. Interactions between photons in such an atomic medium can be many orders of magnitude stronger than in conventional optical materials
Linewidth of collimated wavelength-converted emission in Rb vapour
We present a study of the spectral linewidth of collimated blue light (CBL) that results from wave mixing of low-power continuous-wave laser radiation at 780 and 776 nm and an internally generated mid-IR field at 5.23 μm in Rb vapour. Using a high-finesse Fabry–Perot interferometer, the spectral width of the CBL is found to be <1.3 MHz for a wide range of experimental conditions. We demonstrate using frequency-modulated laser light that the CBL linewidth is mainly limited by the temporal coherence of the applied laser fields rather than the atom–light interaction itself. The obtained result allows the same 1.3 MHz upper limit to be set for the linewidth of the collimated mid-IR radiation at 5.23 μm, which has not been directly detected.Alexander Akulshin, Christopher Perrella, Gar-Wing Truong, Andre Luiten, Dmitry Budker, Russell McLea
Generation and manipulation of Schrödinger cat states in Rydberg atom arrays
2017 © The Authors Quantum entanglement involving coherent superpositions of macroscopically distinct states is among the most striking features of quantum theory, but its realization is challenging because such states are extremely fragile. Using a programmable quantum simulator based on neutral atom arrays with interactions mediated by Rydberg states, we demonstrate the creation of “Schrödinger cat” states of the Greenberger-Horne-Zeilinger (GHZ) type with up to 20 qubits. Our approach is based on engineering the energy spectrum and using optimal control of the many-body system. We further demonstrate entanglement manipulation by using GHZ states to distribute entanglement to distant sites in the array, establishing important ingredients for quantum information processing and quantum metrology