Protecting dissipative quantum state preparation via dynamical decoupling

We show that dissipative quantum state preparation processes can be protected against qubit dephasing by interlacing the state preparation control with dynamical decoupling (DD) control consisting of a sequence of short $\pi$-pulses. The inhomogeneous broadening can be suppressed to second order of the pulse interval, and the protection efficiency is nearly independent of the pulse sequence but determined by the average interval between pulses. The DD protection is numerically tested and found to be efficient against inhomogeneous dephasing on two exemplary dissipative state preparation schemes that use collective pumping to realize many-body singlets and linear cluster states respectively. Numerical simulation also shows that the state preparation can be efficiently protected by $\pi$-pulses with completely random arrival time. Our results make possible the application of these state preparation schemes in inhomogeneously broadened systems. DD protection of state preparation against dynamical noises is also discussed using the example of Gaussian noise with a semiclasscial description.Comment: 9 pages, 8 figure

Spin filtering implemented through Rashba and weak magnetic modulations

We present two theoretical schemes for spin filters in one-dimensional semiconductor quantum wires with spatially modulated Rashba spin-orbit coupling (SOC) as well as weak magnetic potential. For case I, the SOC is periodic and the weak magnetic potential is applied uniformly along the wire. Full spin polarizations with opposite signs are obtained within two separated energy intervals. For case II, the weak magnetic potential is periodic while the SOC is uniform. An ideal negative/positive switching effect for spin polarization is realized by tuning the strength of SOC. The roles of SOC, magnetic potential, and their coupling on the spin filtering are analyzed.Comment: 4 pages, 4 figure

On the Design of Secure and Fast Double Block Length Hash Functions

In this work the security of the rate-1 double block length hash functions, which based on a block cipher with a block length of n-bit and a key length of 2n-bit, is reconsidered. Counter-examples and new attacks are presented on this general class of double block length hash functions with rate 1, which disclose uncovered flaws in the necessary conditions given by Satoh et al. and Hirose. Preimage and second preimage attacks are presented on Hirose's two examples which were left as an open problem. Therefore, although all the rate-1 hash functions in this general class are failed to be optimally (second) preimage resistant, the necessary conditions are refined for ensuring this general class of the rate-1 hash functions to be optimally secure against the collision attack. In particular, two typical examples, which designed under the refined conditions, are proven to be indifferentiable from the random oracle in the ideal cipher model. The security results are extended to a new class of double block length hash functions with rate 1, where one block cipher used in the compression function has the key length is equal to the block length, while the other is doubled

Consolidation of P2Y12 Testing While Maintaining Quality and Turnaround Time

Objective: To consolidate the test performed at 2 different locations at 1, thereby improving cost effectiveness while maintaining quality and result turnaround time.https://jdc.jefferson.edu/patientsafetyposters/1059/thumbnail.jp

Quantum anti-quenching of radiation from laser-driven structured plasma channels

We demonstrate that in the interaction of a high-power laser pulse with a structured solid-density plasma-channel, clear quantum signatures of stochastic radiation emission manifest, disclosing a novel avenue to studying the quantized nature of photon emission. In contrast to earlier findings we observe that the total radiated energy for very short interaction times, achieved by studying thin plasma channel targets, is significantly larger in a quantum radiation model as compared to a calculation including classical radiation reaction, i.e., we observe quantum anti-quenching. By means of a detailed analytical analysis and a refined test particle model, corroborated by a full kinetic plasma simulation, we demonstrate that this counter-intuitive behavior is due to the constant supply of energy to the setup through the driving laser. We comment on an experimental realization of the proposed setup, feasible at upcoming high-intensity laser facilities, since the required thin targets can be manufactured and the driving laser pulses provided with existing technology.Comment: 6 pages, 3 figure