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.
CONSPECTUS:Programming nanoscale functional objects into complex,sophisticated heterostructures that tremendously outperform their solo objects and even bring about exotic chemical/physical properties offers exciting routes toward a spectrum of applications in photonics and electronics.The development in synthetic chemistry over past decades has enabled a library of hybrid nanostructures,such as core−shell,patchy,dimer,hierarchical/branched ones,etc.Nevertheless,the material combinations of these non-van der Waals solids are largely limited by the rule of lattice-matched epitaxy thereof.As an emerging class of heterostructures,axially segmented nanowires(ASNWs)offer an alternative but effective approach to epitaxially integrating the conventional non-van der Waals solids.The large lattice-mismatch tolerance in ASNWs permits vast material combinations,broad size modulations,and flexible interfacial strain engineering,signifying the great potentials for engineering their photon utilizations,band structures,features of charge carriers or excitons,and some other emerging properties.Unfortunately,ASNWs with on-demand,high-precision control over composition,shape,dimension,crystal phase,interface,and periodicity remain so far synthetically challenging.By steering the chemoselective reactions,one has access to high-precision ASNWs.In this Account,we describe the state-of-the-art synthetic strategies for chemoselectivity control.We categorize them into(i)unidirectional/bidirectional sequential additions,which include selective area epitaxy,catalyzed growth,and end-facet-seeded growth,and(ii)regiospecific one-off transformations,which include ionic exchange reaction,strain/thermal induced phase segregation and transition,Plateau-Rayleigh instability,regioselective heterogeneous nucleation as ruled by lattice match,defect,and surface charges,and nanomasking.We uncover the chemical principles behind from thermodynamic and kinetic aspects.Then we further offer insights into their fundamental physics(including carrier/photo
Yi LiTao-Tao ZhuangChong ZhangLiang WuShi-Kui HanShu-Hong Yu
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
