22 research outputs found
Correction of Arbitrary Errors in Population Inversion of Quantum Systems by Universal Composite Pulses
We introduce universal broadband composite pulse sequences for robust
high-fidelity population inversion in two-state quantum systems, which
compensate deviations in any experimental parameter (e.g. pulse amplitude,
pulse duration, detuning from resonance, Stark shifts, unwanted frequency
chirp, etc.) and are applicable with any pulse shape. We demonstrate the
efficiency and universality of these composite pulses by experimental data on
rephasing of atomic coherences in a
crystal
Experimental demonstration of composite stimulated Raman adiabatic passage
We experimentally demonstrate composite stimulated Raman adiabatic passage
(CSTIRAP), which combines the concepts of composite pulse sequences and
adiabatic passage. The technique is applied for population transfer in a
rare-earth doped solid. We compare the performance of CSTIRAP with conventional
single and repeated STIRAP, either in the resonant or the highly detuned
regime. In the latter case, CSTIRAP improves the peak transfer efficiency and
robustness, boosting the transfer efficiency substantially compared to repeated
STIRAP. We also propose and demonstrate a universal version of CSTIRAP, which
shows improved performance compared to the originally proposed composite
version. Our findings pave the way towards new STIRAP applications, which
require repeated excitation cycles, e.g., for momentum transfer in atom optics,
or dynamical decoupling to invert arbitrary superposition states in quantum
memories.Comment: 11 pages, 5 figure
Universal Composite Pulses for Efficient Population Inversion with an Arbitrary Excitation Profile
We introduce a method to rotate arbitrarily the excitation profile of
universal broadband composite pulse sequences for robust high-fidelity
population inversion. These pulses compensate deviations in any experimental
parameter (e.g. pulse amplitude, pulse duration, detuning from resonance, Stark
shifts, unwanted frequency chirp, etc.) and are applicable with any pulse
shape. The rotation allows to achieve higher order robustness to any
combination of pulse area and detuning errors at no additional cost. The latter
can be particularly useful, e.g., when detuning errors are due to Stark shifts
that are correlated with the power of the applied field. We demonstrate the
efficiency and universality of these composite pulses by experimental
implementation for rephasing of atomic coherences in a
crystal.Comment: arXiv admin note: text overlap with arXiv:1403.120
Dynamical suppression of unwanted transition paths in multistate quantum systems
We introduce a method to suppress unwanted transition channels, even without
knowing their couplings, and achieve perfect population transfer in multistate
quantum systems by the application of composite pulse sequences. Unwanted
transition paths may be present due to imperfect light polarization, stray
electromagnetic fields, misalignment of quantization axis, spatial
inhomogeneity of trapping fields, off-resonant couplings, etc. Compensation of
simultaneous deviations in polarization, pulse area, and detuning is
demonstrated. The accuracy, the flexibility and the robustness of this
technique make it suitable for high-fidelity applications in quantum optics and
quantum information processing.Comment: 5 figure
Arbitrarily Accurate Pulse Sequences for Robust Dynamical Decoupling
We introduce universally robust sequences for dynamical decoupling, which
simultaneously compensate pulse imperfections and the detrimental effect of a
dephasing environment to an arbitrary order, work with any pulse shape, and
improve performance for any initial condition. Moreover, the number of pulses
in a sequence grows only linearly with the order of error compensation. Our
sequences outperform the state-of-the-art robust sequences for dynamical
decoupling. Beyond the theoretical proposal, we also present convincing
experimental data for dynamical decoupling of atomic coherences in a
solid-state optical memory
Subcutaneous nephrovesical bypass in a patient with advanced prostate cancer
In the presence of hydronephrosis, as a result of ureteral malignant invasion, advanced pelvic tumor or retroperitoneal fibrosis, we most often perform a double J stent or percutaneous nephrostomy. In the search for a better quality of life for our patients in recent years in urological practice is increasingly becoming the use of subcutaneous nephrovesical bypass due to its proven safety, effectiveness and minimal invasiveness