102 research outputs found
Non-disturbance criteria of quantum measurements
Using the general sequential product proposed by Shen and Wu in [J. Phys. A:
Math. Theor. 42, 345203, 2009], we derive three criteria for describing
non-disturbance between quantum measurements that may be unsharp with such new
sequential products, which generalizes Gudder's results
Tighter uncertainty relations based on modified weighted Wigner-Yanase-Dyson skew information of quantum channels
We use a novel formation to illustrate the () modified
weighted Wigner-Yanase-Dyson (() MWWYD) skew information
of quantum channels. By using operator norm inequalities, we explore the sum
uncertainty relations for arbitrary quantum channels and for unitary
channels. These uncertainty inequalities are shown to be tighter than the
existing ones by a detailed example. Our results are also applicable to the
modified weighted Wigner-Yanase-Dyson (MWWYD) skew information and the
() modified weighted Wigner-Yanase-Dyson (()
MWWYD) skew information of quantum channels as special cases.Comment: 12 pages, 2 figure
Average skew information-based coherence and its typicality for random quantum states
We study the average skew information-based coherence for both random pure
and mixed states. The explicit formulae of the average skew information-based
coherence are derived and shown to be the functions of the dimension N of the
state space. We demonstrate that as N approaches to infinity, the average
coherence is 1 for random pure states, and a positive constant less than 1/2
for random mixed states. We also explore the typicality of average skew
information-based coherence of random quantum states. Furthermore, we identify
a coherent subspace such that the amount of the skew information-based
coherence for each pure state in this subspace can be bounded from below almost
always by a fixed number that is arbitrarily close to the typical value of
coherence.Comment: 24page
Coherence and complementarity based on modified generalized skew information
We introduce modified generalized Wigner-Yanase-Dyson (MGWYD) skew
information and modified weighted generalized Wigner-Yanase-Dyson (MWGWYD) skew
information. By revisiting state-channel interaction based on MGWYD skew
information, a family of coherence measures with respect to quantum channels is
proposed. Furthermore, explicit analytical expressions of these coherence
measures of qubit states are derived with respect to different quantum
channels. Moreover, complementarity relations based on MGWYD skew information
and MWGWYD skew information are also presented. Specifically, the conservation
relations are investigated, while two interpretations of them including
symmetry-asymmetry complementarity and wave-particle duality have been
proposed.Comment: 20page
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
Uncertainty Relations Based on Modified Wigner-Yanase-Dyson Skew Information
Uncertainty relation is a core issue in quantum mechanics and quantum
information theory. We introduce modified generalized Wigner-Yanase-Dyson
(MGWYD) skew information and modified weighted generalizedWigner-Yanase-Dyson
(MWGWYD) skew information, and establish new uncertainty relations in terms of
the MGWYD skew information and MWGWYD skew information.Comment: 16 page
Efficiency at maximum power output of quantum heat engines under finite-time operation
We study the efficiency at maximum power, , of irreversible quantum
Carnot engines (QCEs) that perform finite-time cycles between a hot and a cold
reservoir at temperatures and , respectively. For QCEs in the
reversible limit (long cycle period, zero dissipation), becomes
identical to Carnot efficiency . For QCE cycles in
which nonadiabatic dissipation and time spent on two adiabats are included, the
efficiency at maximum power output is bounded from above by
and from below by . In the
case of symmetric dissipation, the Curzon-Ahlborn efficiency
is recovered under the condition that
the time allocation between the adiabats and the contact time with the
reservoir satisfy a certain relation.Comment: to be published in Phys. Rev. E (2012
The driving factors of spatial differences on the whole life cycle carbon emissions of the construction industry: from the analysis perspective of total factor productivity
The energy saving and emissions reduction of the construction industry are crucial for China to achieve the “carbon peaking and carbon neutrality” goals. In order to promote the green development of the life cycle of the construction industry and improve the efficiency of emissions reduction. This paper examines the spatial-temporal distribution of life cycle carbon emissions in China’s construction industry (LCCECI) from 2004 to 2018. It uses the SBM-Malmquist total factor productivity (TFP) index to measure technological progress and establishes the spatial econometric model based on the STIRPAT model. The study investigates the driving factors of the LCCECI at the provincial and regional levels, aiming to provide suggestions for low-carbon development in the construction industry. The research results are as follows. ① The growth in the SBM-Malmquist TFP index of the construction industry distinctly curbs the LCCECI. ② Total population and urbanization level are not the primary driving factors for the LCCECI. The growth of per capita GDP significantly induces the LCCECI, while concurrently exhibiting a notable inhibitory effect on the LCCECI of neighboring regions. ③ The improvement of the SBM-Malmquist TFP index is conducive to the reduction of the LCCECI in the three major regions. The per capita GDP has the largest positive driving effect of the LCCECI in the eastern region, and the urbanization level the urbanization rate only significantly inhibits the growth of the LCCECI in the central region
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