The measurement of the weak magnetic field in nanoscale resolution and at room temperature is always a significant topic in biological, physical, and material science. Such detection can be used to decide the characterization of the samples, such as cells, materials, and so on. Nitrogen-vacancy (NV) center in diamond has been proved to be able to detect a magnetic field with nano Tesla sensitivity and nanometer resolution at room temperature. Here we experimentally demonstrate an optimized NV center based single electron magnetometer in a commercial diamond and under a home-built optically detected magnetic resonance (ODMR) microscope. With current technology, we change the optically detected time window to get a better signal to noise ratio, and use dynamical decoupling to increase the slope of magnetic field amplitude versus fluorescence signal. By employing the 8-pulse XY-4 dynamical decoupling sequence we achieve a sensitivity of 18.9 nT (Hz)(1/2) , which is 1.7 times better than spin echo. We also propose a NV center based scanning diamond microscope for electron and nuclear spins detection as well as nanoscale magnetic resonance imaging. If it is realized, the NV center based magnetometry will have wide application in the future.
Topological orders are a class of exotic states of matter characterized by patterns of long-range entanglement. Certain topologically ordered systems are proposed as potential realization of fault-tolerant quantum computation. Topological orders can arise in two-dimensional spin-lattice models. In this paper, we engineer a time-dependent Hamiltonian to prepare a topologically ordered state through adiabatic evolution. The other sectors in the degenerate ground-state space of the model are obtained by applying nontrivial operations corresponding to closed string operators. Each sector is highly entangled, as shown from the completely reconstructed density matrices. This paves the way towards exploring the properties of topological orders and the application of topological orders in topological quantum memory.
ZhiHuang LuoJun LiZhaoKai LiLing-Yan HungYi Dun WanXinHua PengJiangFeng Du
Constructing two-dimensional(2D)structures for transition-metal oxides(TMOs)can optimize their electronic structures and enable high specific surface areas,thereby offering routes to enhancing the performance of TMOs in energy storage and conversion.However,most 2D TMOs,e.g.,Fe_(2)O^(3),remain so far synthetically challenging due to their intrinsic non-layered structures.Herein,inspired by the mechanism of biomineralization,we report the synthesis of CuO/Fe_(2)O^(3)hybrid ultrathin nanosheets by using polyvinylpyrrolidone-decorated CuO nanosheets as growth modifiers to modulate the hydrolysis process of Fe^(2+).The formulated“absorption-and-crystallization”two-step formation processes of such 2D hybrid structures accorded well with the biomineralization scheme in nature.Combining the in-situ transmission electron microscopy(TEM)study,theoretical calculation,and control experiments,we validated that the large density of 2D/2D interfaces enabled by this bio-inspired synthesis process can overcome the self-stacking phenomenon during lithium-ion battery cycling,leading to their high operation stability.This work emphasizes the bio-inspired synthesis of 2D TMOs as a promising pathway toward material design and performance optimization.
Quantum superposition is a fundamental principle of quantum mechanics, so it is not surprising that equal superposition states(ESS) serve as powerful resources for quantum information processing. In this work, we propose a quantum circuit that creates an arbitrary dimensional ESS. The circuit construction is efficient as the number of required elementary gates scales polynomially with the number of required qubits. For experimental realization of the method, we use techniques of nuclear magnetic resonance(NMR). We have succeeded in preparing a 9-dimensional ESS on a 4-qubit NMR quantum register. The full tomography indicates that the fidelity of our prepared state with respect to the ideal 9-dimensional ESS is over 96%. We also prove the prepared state is pseudo-entangled by directly measuring an entanglement witness operator. Our result can be useful for the implementation of those quantum algorithms that require an ESS as an input state.
Qi YuYanBao ZhangJun LiHengYan WangXinHua PengJiangFeng Du
Introducing heating function to oil sorbents opens up a new pathway to the fast cleanup of viscous crude oil spills in situ.The oil sorption speed increases with the rise of the temperature,thus oil sorbents with high heating temperature are desirable.Besides,the oil sorbents also need to be produced environment-friendly.Here we present carbonized melamine-formaldehyde sponges(CMSs)that exhibited superior heating performance and the CMSs could be massively fabricated through a non-polluting pyrolysis process.The conductive CMSs could be heated over 300℃with a low applied voltage of 6.9 V and keep above 250℃for 30 min in the air without obvious damage.Such high heating performance enabled heating up the oil spills with a high rate of 2.65℃·s^(-1) and 14%improvement of oil sorption coefficient compared with the state-of-the-art value.We demonstrated that one joule-heated CMS could continuously and selectively collect viscous oil spills(9,010 mPa·s)690 times its own weight in one hour.The CMSs will be a highly competitive sorbent material for the fast remediation of future crude oil spills.
Siloxane rubber shows attractive properties of high stability,elasticity and transparency.Besides,the regulation of its properties renders it widely used in many application fields.However,most of the reported performance improvement methods of siloxane rubber focus on the change of chemical composition of siloxane rubber,including the design of molecular chain and the introduction of other compounds,etc.Such a strategy is still faced with many limitations in practical application.In this work,on the premise of not changing the chemical composition of siloxane rubber,we propose a facile solvothermal polymerization process to change the structure of cross-linking networks,so as to obtain the siloxane rubber with controllable mechanical properties.Compared to the normal curing method,we realized polydimethylsiloxane elastomer(PDMS)with maximum elongation of more than 3,000%(>10 times of normally cured one)and tensile modulus lower than 0.15 MPa(<1/10 of normally cured one).In addition to superior stretchability,it gains extra high softness,stickiness and sensitive response to organic solvents.Based on our solvothermal cured PDMS,its applications in oil collection and organic solvent sensor have been demonstrated.It is expected that this method can be readily utilized widely and shows great application potentials.
Jin HuangYuchun CaiChengyuan XueJin GeHaoyu ZhaoShu-Hong Yu
The Unruh effect is one of the most fundamental manifestations of the fact that the particle content of a field theory is observer dependent. However, there has been so far no experimental verification of this effect, as the associated temperatures lie far below any observable threshold. Recently, physical phenomena, which are of great experimental challenge, have been investigated by quantum simulations in various fields. Here we perform a proof-of-principle simulation of the evolution of fermionic modes under the Unruh effect with a nuclear magnetic resonance(NMR) quantum simulator. By the quantum simulator, we experimentally demonstrate the behavior of Unruh temperature with acceleration, and we further investigate the quantum correlations quantified by quantum discord between two fermionic modes as seen by two relatively accelerated observers. It is shown that the quantum correlations can be created by the Unruh effect from the classically correlated states. Our work may provide a promising way to explore the quantum physics of accelerated systems.
Fang Zhou JinHong Wei ChenXing RongHui ZhouMing Jun ShiQi ZhangChen Yong JuYi Fu CaiShun Long LuoXin Hua PengJiang Feng Du
