120 research outputs found
(1S,4S)-2-(2,4-Difluorophenyl)-5-[(4-methylphenyl)sulfonyl]-2,5-diazabicyclo[2.2.1]heptane
In the title molecule, C18H18F2N2O2S, the two benzene rings, which are oriented in opposite directions with respect to the rigid 2,5-diazabicyclo[2.2.1]heptane core, form a dihedral angle of 17.2 (1)°. Weak intermolecular C—H⋯O, C—H⋯F and C—H⋯N contacts consolidate the crystal packing
6-Oxo-5-[(trifluoromethyl)sulfonyl]-1,2,4a,5,6,11b-hexahydro-1,3-dioxolo[4,5-j]phenanthridin-2-yl benzoate
In the title compound, C22H16F3NO7S, the two benzene rings are almost perpendicular, the dihedral angle between their mean planes being 87.1 (1)°. The terminal O atom of the benzoate moiety is disordered over two positions with site occupancies of 0.244 (15) and 0.756 (15). The crystal structure is stablized by two types of weak intermolecular C—H⋯O hydrogen bonds
Robust retrieval of material chemical states in X-ray microspectroscopy
X-ray microspectroscopic techniques are essential for studying morphological
and chemical changes in materials, providing high-resolution structural and
spectroscopic information. However, its practical data analysis for reliably
retrieving the chemical states remains a major obstacle to accelerating the
fundamental understanding of materials in many research fields. In this work,
we propose a novel data formulation model for X-ray microspectroscopy and
develop a dedicated unmixing framework to solve this problem, which is robust
to noise and spectral variability. Moreover, this framework is not limited to
the analysis of two-state material chemistry, making it an effective
alternative to conventional and widely-used methods. In addition, an
alternative directional multiplier method with provable convergence is applied
to obtain the solution efficiently. Our framework can accurately identify and
characterize chemical states in complex and heterogeneous samples, even under
challenging conditions such as low signal-to-noise ratios and overlapping
spectral features. Extensive experimental results on simulated and real
datasets demonstrate its effectiveness and reliability.Comment: 12 page
Sub-Planck structures and sensitivity of the superposed photon-added or photon-subtracted squeezed-vacuum states
The Wigner function of the compass state (a superposition of four coherent
states) develops phase-space structures of dimension much less than the Planck
scale, which are crucial in determining the sensitivity of these states to
phase-space displacements. In the present work, we introduce compass-like
states that may have connection to the contemporary experiments, which are
obtained by either adding photons to or subtracting photons from the
superposition of two squeezed-vacuum states. We show that, when a significant
quantity of photons is added (or subtracted), the Wigner function of these
states are shown to have phase-space structures of an area that is
substantially smaller than the Planck scale. In addition, these states exhibit
sensitivity to displacements that is much higher than the standard quantum
limit. Finally, we show that both the size of the sub-Planck structures and the
sensitivity of our states are strongly influenced by the average photon number,
with the photon addition case having a higher average photon number leading to
the smaller sub-Planck structures and, consequently, being more sensitive to
displacement than the photon subtraction case. Our states offer unprecedented
resolution to the external perturbations, making them suitable for quantum
sensing applications.Comment: PHYSICAL REVIEW A 107, 052614 (2023), 15 Figures, 20 page
Photo-Otto engine with quantum correlations
We theoretically prose and investigate a photo-Otto engine that is working
with a single-mode radiation field inside an optical cavity and alternatively
driven by a hot and a cold reservoir, where the hot reservoir is realized by
sending one of a pair of correlated two-level atoms to pass through the optical
cavity, and the cold one is made of a collection of noninteracting boson modes.
In terms of the quantum discord of the pair of atoms, we derive the analytical
expressions for the performance parameters (power and efficiency) and stability
measure (coefficient of variation for power). We show that quantum discord
boosts the performance and efficiency of the quantum engine, and even may
change the operation mode. We also demonstrate that quantum discord improves
the stability of machine by decreasing the coefficient of variation for power
which satisfies the generalized thermodynamic uncertainty relation. Finally, we
find that these results can be transferred to another photo-Otto engine model,
where the optical cavity is alternatively coupled to a hot thermal bosonic bath
and to a beam of pairs of the two correlated atoms that play the role of a cold
reservoir
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