Wu-Bin Yang

Quantum-memory-assisted entropic uncertainty relation under noise

The measurement outcomes of two incompatible observables on a particle can be precisely predicted when it is maximally entangled with a quantum memory. In this work, we explore the behavior of the quantum-memory-assisted entropic uncertainty relation under the influence of local unital and nonunital noisy channels. For a class of Bell-diagonal states, we demonstrate that while the unital noises only increase the amount of uncertainty, the amplitude-damping nonunital noisesmay reduce the amount of uncertainty in the long-time limit. The mechanism behind this phenomenon is also explored by using two dissimilar methods.

Proposed method for direct measurement of the non-Markovian character of the qubits coupled to bosonic reservoirs

Non-Markovianity is a recently proposed characterization of the non-Markovian behavior in an open quantum system, based on which we first present a practical idea for directly measuring the non-Markovian character of a single qubit coupled to a zero-temperature bosonic reservoir, and then extend to investigate the dynamics of two noninteracting qubits subject to two reservoirs, respectively, with a lower bound of non-Markovianity. Our scheme, with no need for optimization procedures and quantum state tomography, is helpful for experimental implementation.

Isotopic evidence for continental ice sheet in mid-latitude region in the supergreenhouse Early Cretaceous

Cretaceous represents one of the hottest greenhouse periods in the Earths history, but some recent studies suggest that small ice caps might be present in non-polar regions during certain periods in the Early Cretaceous. Here we report extremely negative δ18O values of −18.12‰ to −13.19‰ for early Aptian hydrothermal zircon from an A-type granite at Baerzhe in northeastern China. Given that A-type granite is anhydrous and that magmatic zircon of the Baerzhe granite has δ18O value close to mantle values, the extremely negative δ18O values for hydrothermal zircon are attributed to addition of meteoric water with extremely low δ18O, mostly likely transported by glaciers. Considering the paleoaltitude of the region, continental glaciation is suggested to occur in the early Aptian, indicating much larger temperature fluctuations than previously thought during the supergreenhouse Cretaceous. This may have impact on the evolution of major organism in the Jehol Group during this period.

Age, petrogenesis and tectonic significance of the ferrobasalts in the Chagangnuoer iron deposit, western Tianshan

The formation of large iron deposits associated with subduction and its genetic relationships with ferrobasalts are not yet well understood. Here we report a geochemical and geochronological investigation on the newly discovered ferrobasalts associated with the Chagangnuoer iron deposit, western Tianshan. The Chagangnuoer ferrobasalts are characterized by high Fe2O3T (14.55–22.68 wt.%) and MnO (0.36–0.93 wt.%) but low TiO2 (0.70–1.26 wt.%) contents. Analyses of 10 zircon grains yield a weighted zircon U–Pb age of 314 ± 8 Ma. Based on our new petrological and geochemical data, we conclude that the Chagangnuoer ferrobasalts probably have been originated from the partial melting of a spinel peridotite mantle source that has been modified by subduction related fluids. The ferrobasalts have nearly linear positive correlation between MnO and (87Sr/86Sr)i, implying the involvement of subducted Fe–Mn nodules. The mid-ocean ridge basalt (MORB)- and ocean island basalt (OIB)-like geochemical features, as well as moderate Ti/V values (18–36), indicate that the ferrobasalts may have been formed in an extensional back-arc basin setting. Combined with previous studies on the Chagangnuoer iron deposit, we propose a hypothesis that the overlying iron orebodies were likely derived from the ferrobasaltic magma.

Implementation of three-qubit Grover search in cavity quantum electrodynamics

Using resonant interaction of three Rydberg atoms with a single-mode microwave cavity, we consider a realization of three-qubit Grover search algorithm in the presence of weak cavity decay, based on a previous idea for three-qubit quantum gate [Phys. Rev. A 73, 064304 (2006)]. We simulate the searching process under the influence of the cavity decay and show that our scheme could be achieved efficiently to find the marked state with high fidelity. The required operations are very close to the reach with current cavity QED techniques.

Chemical lattice expansion of natural zircon during the magmatic-hydrothermal evolution of A-type granite

Abstract Although thermal lattice expansion is a well-documented nature of crystals, including zircon and zircon-type minerals, chemical lattice expansion of natural mineral is rarely reported. Here we present a comprehensive investigation on three types of natural zircon that records the evolution of the granitic system in Xiangshan, North China, and shows expanding crystallographic parameters induced by chemical incorporation instead of thermal expansion. Prismatic and oscillatory-zoned zircon grains (Type-1A), crystallized early in the granitic magma at high temperatures in a volatile-undersaturated environment, have the smallest lattice parameters (a = 6.603 Å, c = 5.971 Å). Prismatic and altered zircon grains (Type-1B), formed under volatile-saturated conditions and in the presence of F-rich fluid with numerous thorite and xenotime inclusions, have intermediate lattice parameters (a = 6.649 Å, c = 6.020 Å). Pyramidal zircon grains (Type-2), formed in a subsolvus granitic system at relatively low temperatures and coexisted with fluid inclusions, have the biggest lattice parameters (a = 6.677 Å, c = 6.010 Å). Trace elements, including Hf, Th, Ti, Y, and REE, and volatiles content, increase in the structure of zircon from the early to late magmatic origin, which is consistent with the expansion of the lattice parameters. The occurrence of the three zircon types in the Xiangshan arfvedsonite granites is interpreted to reflect the progressive fractionation of granitic melt from hypersolvus to subsolvus conditions. Therefore, we conclude that the lattice expansion of zircon in this study results from chemical incorporation of trace element and volatile components during the magmatic to hydrothermal evolution of granitic magma. Besides, the textural and compositional evolution of zircon can be used as efficient indices for the fractionation and evolution of A-type granitic system.

Cooling a mechanical resonator to the quantum regime by heating it

We consider a mechanical resonator made of diamond, which contains a nitrogen-vacancy center (NV center) locating at the end of the oscillator. A second-order magnetic gradient is applied and induces coupling between mechanical modes and the NV center. By applying a proper external magnetic field, the energy difference between NV center electron spin levels can be tuned to match the energy difference between two mechanical modes

Exploring the quantum critical behaviour in a driven Tavis–Cummings circuit

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Nonlinear coupling between a nitrogen-vacancy-center ensemble and a superconducting qubit

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Preparation of cluster states with endohedral fullerenes in single-walled carbon nanotubes

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