246 research outputs found
Design and analysis of digital communication within an SoC-based control system for trapped-ion quantum computing
Electronic control systems used for quantum computing have become
increasingly complex as multiple qubit technologies employ larger numbers of
qubits with higher fidelity targets. Whereas the control systems for different
technologies share some similarities, parameters like pulse duration,
throughput, real-time feedback, and latency requirements vary widely depending
on the qubit type. In this paper, we evaluate the performance of modern
System-on-Chip (SoC) architectures in meeting the control demands associated
with performing quantum gates on trapped-ion qubits, particularly focusing on
communication within the SoC. A principal focus of this paper is the data
transfer latency and throughput of several high-speed on-chip mechanisms on
Xilinx multi-processor SoCs, including those that utilize direct memory access
(DMA). They are measured and evaluated to determine an upper bound on the time
required to reconfigure a gate parameter. Worst-case and average-case bandwidth
requirements for a custom gate sequencer core are compared with the
experimental results. The lowest-variability, highest-throughput data-transfer
mechanism is DMA between the real-time processing unit (RPU) and the PL, where
bandwidths up to 19.2 GB/s are possible. For context, this enables
reconfiguration of qubit gates in less than 2\mics\!, comparable to the fastest
gate time. Though this paper focuses on trapped-ion control systems, the gate
abstraction scheme and measured communication rates are applicable to a broad
range of quantum computing technologies
High-Resolution Studies of Tropolone in the S 0 and S 1 Electronic States: Isotope Driven Dynamics in the Zero-Point Energy Levels
Rotationally resolved microwave (MW) and ultraviolet (UV) spectra of jet-cooled tropolone have been obtained in S0 and S1 electronic states using Fourier-transform microwave and UV-laser/molecular-beam spectrometers. In the ground electronic state, the MW spectra of all heavy-atom isotopomers including one O18 and four C13 isotopomers were observed in natural abundance. The OD isotopomer was obtained from isotopically enriched samples. The two lowest tunneling states of each isotopomer except O18 have been assigned. The observed inversion splitting for the OD isotopomer is 1523.227(5) MHz. For the asymmetric C13 structures, the magnitudes of tunneling-rotation interactions are found to diminish with decreasing distance between the heavy atom and the tunneling proton. In the limit of closest approach, the 0+ state of O18 was well fitted to an asymmetric rotor Hamiltonian, reflecting significant changes in the tautomerization dynamics. Comparisons of the substituted atom coordinates with theoretical predictions at the MP2/aug-cc-pVTZ level of theory suggest the localized 0+ and 0â wave functions of the heavier isotopes favor the CâOH and C=O forms of tropolone, respectively. The only exception occurs for the C13-OH and C13=O structures which correlate to the 0â and 0+ states, respectively. These preferences reflect kinetic isotope effects as quantitatively verified by the calculated zero-point energy differences between members of the asymmetric atom pairs. From rotationally resolved data of the 0+â0+ and 0ââ0â bands in S1, line-shape fits have yielded Lorentzian linewidths that differ by 12.2(16) MHz over the 19.88(4)cmâ1 interval in S1. The fluorescence decay rates together with previously reported quantum yield data give nonradiative decay rates of 7.7(5)Ă108 and 8.5(5)Ă108sâ1 for the 0+ and 0â levels of the S1 state of tropolone
The interplay between conformation and absolute configuration in chiral electron dynamics of small diols
A competition between chiral characteristics alternatively attributable to either conformation or to absolute configuration is identified. Circular dichroism associated with photoexcitation of the outer orbital of configurational enantiomers of 1,3- and 2,3-butanediols has been examined with a focus on the large changes in electron chiral asymmetry produced by different molecular conformations. Experimental gas phase measurements offer support for the theoretical modelling of this chiroptical effect. A surprising prediction is that a conformationally produced pseudoenantiomerism in 1,3-butanediol generates a chiral response in the frontier electron dynamics that effectively outweighs the influence of the permanent configurational handedness established at the asymmetrically substituted carbon. Induced conformation, and specifically induced conformational chirality, may thus be a dominating factor in chiral molecular recognition in such systems
Exploring the conformational dynamics of alanine dipeptide in solution subjected to an external electric field: A nonequilibrium molecular dynamics simulation
In this paper, we investigate the conformational dynamics of alanine
dipeptide under an external electric field by nonequilibrium molecular dynamics
simulation. We consider the case of a constant and of an oscillatory field. In
this context we propose a procedure to implement the temperature control, which
removes the irrelevant thermal effects of the field. For the constant field
different time-scales are identified in the conformational, dipole moment, and
orientational dynamics. Moreover, we prove that the solvent structure only
marginally changes when the external field is switched on. In the case of
oscillatory field, the conformational changes are shown to be as strong as in
the previous case, and non-trivial nonequilibrium circular paths in the
conformation space are revealed by calculating the integrated net probability
fluxes.Comment: 23 pages, 12 figure
The Interplay Between Conformation and Absolute Configuration in Chiral Electron Dynamics of Small Diols
Recent Developments of an Opto-Electronic THz Spectrometer for High-Resolution Spectroscopy
A review is provided of sources and detectors that can be employed in the THz range before the description of an opto-electronic source of monochromatic THz radiation. The realized spectrometer has been applied to gas phase spectroscopy. Air-broadening coefficients of HCN are determined and the insensitivity of this technique to aerosols is demonstrated by the analysis of cigarette smoke. A multiple pass sample cell has been used to obtain a sensitivity improvement allowing transitions of the volatile organic compounds to be observed. A solution to the frequency metrology is presented and promises to yield accurate molecular line center measurements
Ultrafast Laser-Based Spectroscopy and Sensing: Applications in LIBS, CARS, and THz Spectroscopy
Ultrafast pulsed lasers find application in a range of spectroscopy and sensing techniques including laser induced breakdown spectroscopy (LIBS), coherent Raman spectroscopy, and terahertz (THz) spectroscopy. Whether based on absorption or emission processes, the characteristics of these techniques are heavily influenced by the use of ultrafast pulses in the signal generation process. Depending on the energy of the pulses used, the essential laser interaction process can primarily involve lattice vibrations, molecular rotations, or a combination of excited states produced by laser heating. While some of these techniques are currently confined to sensing at close ranges, others can be implemented for remote spectroscopic sensing owing principally to the laser pulse duration. We present a review of ultrafast laser-based spectroscopy techniques and discuss the use of these techniques to current and potential chemical and environmental sensing applications
Photodissociation and photoionisation of atoms and molecules of astrophysical interest
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