10 research outputs found
Efficient optical pumping of Zeeman spin levels in Nd3+:YVO4
We demonstrate that Zeeman ground-state spin levels in Nd3+:YVO4 provides the
possibility to create an efficient lambda-system for optical pumping
experiments. The branching ratio R in the lambda-system is measured
experimentally via absorption spectroscopy and is compared to a theoretical
model. We show that R can be tuned by changing the orientation of the magnetic
field. These results are applied to optical pumping experiments, where
significant improvement is obtained compared to previous experiments in this
system. The tunability of the branching ratio in combination with its good
coherence properties and the high oscillator strength makes Nd3+:YVO4 an
interesting candidate for various quantum information protocols.Comment: 8 pages, 6 figure
Controlled Stark shifts in Er-doped crystalline and amorphous waveguides for quantum state storage
We present measurements of the linear Stark effect on the I I transition in an Er-doped proton-exchanged
LiNbO crystalline waveguide and an Er-doped silicate fiber. The
measurements were made using spectral hole burning techniques at temperatures
below 4 K. We measured an effective Stark coefficient
kHz/Vcm in the crystalline waveguide and
kHz/Vcm in the silicate fiber.
These results confirm the potential of Erbium doped waveguides for quantum
state storage based on controlled reversible inhomogeneous broadening.Comment: 4 pages, 2 figures v2. typo in formula correcte
A solid state light-matter interface at the single photon level
Coherent and reversible mapping of quantum information between light and
matter is an important experimental challenge in quantum information science.
In particular, it is a decisive milestone for the implementation of quantum
networks and quantum repeaters. So far, quantum interfaces between light and
atoms have been demonstrated with atomic gases, and with single trapped atoms
in cavities. Here we demonstrate the coherent and reversible mapping of a light
field with less than one photon per pulse onto an ensemble of 10 millions atoms
naturally trapped in a solid. This is achieved by coherently absorbing the
light field in a suitably prepared solid state atomic medium. The state of the
light is mapped onto collective atomic excitations on an optical transition and
stored for a pre-programmed time up of to 1 mu s before being released in a
well defined spatio-temporal mode as a result of a collective interference. The
coherence of the process is verified by performing an interference experiment
with two stored weak pulses with a variable phase relation. Visibilities of
more than 95% are obtained, which demonstrates the high coherence of the
mapping process at the single photon level. In addition, we show experimentally
that our interface allows one to store and retrieve light fields in multiple
temporal modes. Our results represent the first observation of collective
enhancement at the single photon level in a solid and open the way to multimode
solid state quantum memories as a promising alternative to atomic gases.Comment: 5 pages, 5 figures, version submitted on June 27 200
Investigations of Optical Coherence Properties in an Erbium-doped Silicate Fiber for Quantum State Storage
We studied optical coherence properties of the 1.53 m telecommunication
transition in an Er-doped silicate optical fiber through spectral
holeburning and photon echoes. We find decoherence times of up to 3.8 s at
a magnetic field of 2.2 Tesla and a temperature of 150 mK. A strong
magnetic-field dependent optical dephasing was observed and is believed to
arise from an interaction between the electronic Er spin and the
magnetic moment of tunneling modes in the glass. Furthermore, we observed
fine-structure in the Erbium holeburning spectrum originating from
superhyperfine interaction with Al host nuclei. Our results show that
Er-doped silicate fibers are promising material candidates for quantum
state storage
Preamplification techniques for real-time RT-PCR analyses of endomyocardial biopsies
<p>Abstract</p> <p>Background</p> <p>Due to the limited RNA amounts from endomyocardial biopsies (EMBs) and low expression levels of certain genes, gene expression analyses by conventional real-time RT-PCR are restrained in EMBs. We applied two preamplification techniques, the TaqMan<sup>® </sup>PreAmp Master Mix (T-PreAmp) and a multiplex preamplification following a sequence specific reverse transcription (SSRT-PreAmp).</p> <p>Results</p> <p>T-PreAmp encompassing 92 gene assays with 14 cycles resulted in a mean improvement of 7.24 ± 0.33 Ct values. The coefficients for inter- (1.89 ± 0.48%) and intra-assay variation (0.85 ± 0.45%) were low for all gene assays tested (<4%). The PreAmp uniformity values related to the reference gene CDKN1B for 91 of the investigated gene assays (except for CD56) were -0.38 ± 0.33, without significant differences between self-designed and ABI inventoried Taqman<sup>® </sup>gene assays. Only two of the tested Taqman<sup>® </sup>ABI inventoried gene assays (HPRT-ABI and CD56) did not maintain PreAmp uniformity levels between -1.5 and +1.5. In comparison, the SSRT-PreAmp tested on 8 self-designed gene assays yielded higher Ct improvement (9.76 ± 2.45), however was not as robust regarding the maintenance of PreAmp uniformity related to HPRT-CCM (-3.29 ± 2.40; p < 0.0001), and demonstrated comparable intra-assay CVs (1.47 ± 0.74), albeit higher inter-assay CVs (5.38 ± 2.06; p = 0.01). Comparing EMBs from each 10 patients with dilated cardiomyopathy (DCM) and inflammatory cardiomyopathy (DCMi), T-PreAmp real-time RT-PCR analyses revealed differential regulation regarding 27 (30%) of the investigated 90 genes related to both HPRT-CCM and CDKN1B. Ct values of HPRT and CDKN1B did not differ in equal RNA amounts from explanted DCM and donor hearts.</p> <p>Conclusion</p> <p>In comparison to the SSRT-PreAmp, T-PreAmp enables a relatively simple workflow, and results in a robust PreAmp of multiple target genes (at least 92 gene assays as tested here) by a mean Ct improvement around 7 cycles, and in a lower inter-assay variance in RNA derived from EMBs. Preliminary analyses comparing EMBs from DCM and DCMi patients, revealing differential regulation regarding 30% of the investigated genes, confirm that T-PreAmp is a suitable tool to perform gene expression analyses in EMBs, expanding gene expression investigations with the limited RNA/cDNA amounts derived from EMBs. CDKN1B, in addition to its function as a reference gene for the calculation of PreAmp uniformity, might serve as a suitable housekeeping gene for real-time RT-PCR analyses of myocardial tissues.</p
Coupling of an erbium spin ensemble to a superconducting resonator
A quantum coherent interface between optical and microwave photons can be used as a basic building block within a future quantum information network. The interface is envisioned as an ensemble of rare-earth ions coupled to a superconducting resonator, allowing for coherent transfer between optical and microwave photons. Towards this end, we have realized a hybrid device coupling a Er3 +-doped Y2SiO5 crystal in a superconducting coplanar waveguide cavity. We observe a collective spin coupling of 4 MHz and a spin linewidth of down to 75 MHz