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In this work, a model of optomechanical system was investigated by analyzing the entanglement dynamics of two related mechanical oscillators in a modified system. Geometrical shapes effects of optical cavities on entanglement of a representative optomechanical system were investigated by means of performing numerical analysis. It was signified that the steady-state or the dynamic behavior of optomechanical engagement could be created owing to the strength of mechanical pairs, which are strong towards the oscillating temperature. In addition, the mentioned entanglement dynamics were seen to be entirely related to the natural state’s stability. Furthermore, rendering the mechanical damping effects, the critical mechanical coupling strength-related analytical expression, where the transition from a steady state to a dynamic clamp occurs, was reported. In the studied system, two identical mechanical oscillators were formed in different conditions of the optical cavities shapes.

One deed for two needs-inspired bifunctional MnO2@PPy nanocomposites for solar-driven water evaporation at the rate of 12.31 kg m−2 per day and enhanced photo-thermoelectric power generation with an output power density (Pout ∼ 12.3 W m−2).

Conventional kinesin is a high-performance motor that moves primarily toward the plus end of microtubules and occasionally toward the opposite direction. The physical mechanism of this directional stepping remains unclear. Here we develop a kinetic two-cycle model incorporating kinesin forward and backward stepping, in which the neck linker zippering and ATP catalysis process are conserved in backward steps. This model is quantitatively validated by a variety of experimental data, including load dependence of velocity, stepping ratio, and dwell time. The physical mechanism of kinesin stepping regulated by a biased diffusion process is identified by analyzing the load dependence and relevant thermodynamic properties of the model. Furthermore, the model suggests the kinesin directionality is optimized resulting from fulfilling a thermodynamic constraint. Our modeling provides a chemomechanical coupling mechanism that connects the flexibility of the neck linker zippering effect for direction rectification and the measured performance into a consistent frame.

We investigate the single-photon scattering properties of a driven three-level giant atom chirally coupled to two waveguides simultaneously in both the Markovian and the non-Markovian regimes. It is shown that under the Markovian limit, the chiral photon-atom interactions enable nonreciprocal scattering in a single waveguide and targeted photon routing with a probability of 100% in two waveguides, while the presence of the driving field and the giant atom structure introduce a more tunable parameter to manipulate the single-photon scattering behaviors. We also examine how the non-reciprocity and routing capability are influenced by the imperfect chirality and the atomic dissipation. In the non-Markovian regime, we show that the scattering behaviors are more complicated. The non-Markovicity induced non-reciprocity and photon routing are demonstrated in this paper. We believe that those results have potential applications in quantum network engineering.

We propose a novel quantum electrodynamics (QED) platform where quantum emitters interact with a Hofstadter-ladder waveguide. We demonstrate several intriguing phenomena stemming from the exotic dispersion relation and vacuum mode properties led by the effective spin-orbit coupling, which have no analog in other QED setups. First, by assuming emitter's frequency to be resonant with the lower band, we find that the spontaneous emission is chiral with most photonic field decaying unidirectionally. Both numerical and analytical results indicate that the Hofstadter-ladder waveguide can be engineered as a well-performed chiral quantum bus. Second, the dynamics of emitters of giant atom form is explored by considering their frequencies below the lower band. Due to quantum interference, we find that both the emitter-waveguide interaction and the amplitudes of bound states are periodically modulated by giant emitter's size. The periodical length depends on the positions of energy minima points induced by the spin-orbit coupling. Last, we consider the interaction between two giant emitters mediated by bound states, and find that their dipole-dipole interaction vanishes (is enhanced) when maximum destructive (constructive) interference happens., Comment: 13 pages; 8 figures

We propose a scheme consisting of coupled nanomechanical cantilever resonators and superconducting flux qubits to engineer a parity-time- ( P T -) symmetric phononic system formed by active and passive modes. The effective gain (loss) of the phonon mode is achieved by the longitudinal coupling of the resonator and the fast dissipative superconducting qubit with a blue-sideband driving (red-sideband driving). A P T -symmetric to broken- P T -symmetric phase transition can be observed in both balanced gain-to-loss and unbalanced gain-to-loss cases. Applying a resonant weak probe field to the dissipative resonator, we find that (i) for balanced gain and loss, the acoustic signal absorption to amplification can be tuned by changing the coupling strength between resonators; (ii) for unbalanced gain and loss, both acoustically induced transparency and anomalous dispersion can be observed around Δ = 0, where the maximum group delay is also located at this point. Our work provides an experimentally feasible scheme to design P T -symmetric phononic systems and a powerful platform for controllable acoustic signal transmission in a hybrid quantum system.

Designing unconventional interactions between single phonons and spins is fascinating for its applications in quantum phononics. Here, we propose a reliable scheme for coupling spins and phonons in phononic dimer and trimer lattices, with the combination of solid-state defects and diamond phononic (optomechanical) crystals. The dimer and trimer lattices used are an array of coupled phononic cavities with spatially modulated hopping rates. We predict a series of unconventional sound-matter interaction phenomena in this hybrid quantum system. In the dimer lattice, we show the formation of chiral spin-phonon bound states and topology-dependent phononic collective radiation. While in the trimer lattice, chiral bound states still exist and the spin relaxation is sublattice-dependent. The chiral bound states existed in both types of lattices are robust to large amount of disorder, which can mediate chiral and robust spin-spin interactions. This work provides a promising platform for phonon-based quantum information processing and quantum simulation., 13 pages, 10 figures

There has been growing interest in investigating properties of elementary particles predicted by the standard model. Examples of such studies include exploring their low-energy analogs in a condensed-matter system, where they arise as collective states or quasiparticles. Here we show that a toolbox for systematically engineering the emergent elementary fermions, i.e., Dirac, Weyl, and Majorana fermions, can be built in a single atomic system composed of a spinless magnetic dipolar Fermi gas in a three-dimensional optical lattice. The designed direction-dependent dipole-dipole interaction leads to both the basic building block, i.e., in-plane $p+ip$ superfluid pairing instability, and the manipulating tool, i.e., out-of-plane Peierls instability. It is shown that the Peierls instability provides a natural way of tuning the topological nature of $p+ip$ superfluids and can transform the fermion's nature between distinct emergent particles. Our scheme should contribute to the search for elementary particles through manipulating the topology.

The circulator is an important device in quantum information, which can route the input state to a designated output channel. In this work, we propose a scheme to realize a microwave photonic circulator based on optomechanical-like superconducting interactions. Our setup involves three high-frequency (HF) resonators and a low-frequency (LF) resonator. The HF resonators are coupled to the LF frequency resonator by the superconducting quantum interference device, and the HF resonators are coupled each other via linear interactions. Driving the HF resonators with three coherent fields results in synthetic magnetic fluxes, which, in combination with dissipative coupling to the LF resonator’s bath, leads to nonreciprocal transports of microwave photons. Different from circulators based on the optomechanical system, our scheme has stronger coupling and no thermal phonon noise. In the specific phase relationship, we calculate the nonreciprocal condition of the microwave photonic circulator and find that the transmission direction can be controlled by the phase differences between the driving fields. We obtain the parameters that affect the bandwidth. Moreover, we investigate the effects of imperfection. Our results provide a theoretical proposal for the realization of a high-isolation (68.4 dB) and low-dissipation microwave photonic circulator.

Introduction: The present study aimed to examine whether GATA-4 overexpressing bone marrow mesenchymal stem cells can improve cardiac function in a murine myocardial infarction model compared with bone marrow mesenchymal stem cells alone. Methods: A lentiviral-based transgenic system was used to generate bone mesenchymal stem cells which stably expressed GATA-4 (GATA-4-bone marrow mesenchymal stem cells). Apoptosis and the myogenic phenotype of the bone marrow mesenchymal stem cells were measured using Western blot and immunofluorescence assays co-cultured with cardiomyocytes. Cardiac function, bone marrow mesenchymal stem cell homing, cardiac cell apoptosis, and vessel number following transplantation were assessed, as well as the expression of c-Kit. Results: In GATA-4-bone marrow mesenchymal stem cells-cardiomyocyte co-cultures, expression of myocardial-specific antigens, cTnT, connexin-43, desmin, and α-actin was increased compared with bone marrow mesenchymal stem cells alone. Caspase 8 and cytochrome C expression was lower, and the apoptotic rate was significantly lower in GATA-4 bone marrow mesenchymal stem cells. Cardiac function following myocardial infarction was also increased in the GATA-4 bone marrow mesenchymal stem cell group as demonstrated by enhanced ejection fraction and left ventricular fractional shortening. Analysis of the cardiac tissue revealed that the GATA-4 bone marrow mesenchymal stem cell group had a greater number of DiR-positive cells suggestive of increased homing and/or survival. Transplantation with GATA-4-bone marrow mesenchymal stem cells significantly increased the number of blood vessels, decreased the proportion of apoptotic cells, and increased the mean number of cardiac c-kit-positive cells. Conclusion: GATA-4 overexpression in bone marrow mesenchymal stem cells exerts anti-apoptotic effects by targeting cytochrome C and Fas pathways, promotes the aggregation of bone marrow mesenchymal stem cells in cardiac tissue, facilitates angiogenesis, and effectively mobilizes c-kit-positive cells following myocardial infarction, leading to the improvement of cardiac function after MI.

We theoretically investigate force-dependent induced transparency effect of an output field in an atom-assisted optomechanical system where a mechanical resonator is driven by a time-dependent force. It is shown that there exists an additional transparency window besides a standard optomechanical induced transparency window due to the Jaynes–Cummings coupling between a two-level atom and cavity. We find that the transmission amplitude of optomechanical induced transparency effect is largely suppressed or enhanced by adjusting the amplitude and phase of the external force. Benefiting from the atom and the external force, the effect of tunable fast and slow light can be realizable, which may be helpful for quantum information storage processing.

Negative absolute temperature has a wide range of applications, such as high-efficiency quantum heat engines, quantum refrigerators, and quantum simulation. In a recent paper (2018 Phys. Rev. Lett. 120 060403), the authors proposed two spin ensembles coupled to the same reservoir collectively; one ensemble relaxes to negative temperature since the two ensembles have unbalanced spin sizes. However, the coherent coupling mediated by the common environment is not considered. Here, we discuss negative temperature in a system where two qubit-ensembles are coupled to the same 1D waveguide. In the limit of Markovian approximation, by investigating the coherent coupling and non-cross (cross) collective decay between two qubit-ensembles, we find that the duration of the negative temperature state depends on the distance between the two ensembles. The decrease in negative temperature duration is due to the coherent coupling between the two ensembles that will hybridize the unitary evolution of the system. Some optimal points produce the longest duration of negative temperature, but this could not occur since the distance is out of the range of the appropriate regions. The negative temperature subensemble plays the role of a reservoir in the quantum Otto heat engine, which takes place beyond the Otto limit.

In this work, we propose a high-fidelity phonon-mediated entangling gate in a hybrid mechanical system based on two silicon-vacancy color centers in diamond. In order to suppress the influence of the spin decoherence on the entangling gate, we use a continuous dynamical decoupling approach to create new dressed spin states, which are less sensitive to environmental fluctuations and exhibit an extended T 2 * spin dephasing time. The effective spin–spin Hamiltonian modified by the mechanical driving field and the corresponding master equation are derived in the dispersive regime. We show that in the presence of the mechanical driving field, the effective spin–spin coupling can be highly controlled. By calculating the entangling gate fidelity in the dressed basis, we find that once the mechanical field is turned on, the gate fidelity can be significantly improved. In particular, under an optimized spin-phonon detuning and a stronger Rabi frequency of the mechanical driving field, the two-qubit gate is capable of reaching fidelity exceeding 0.99. Moreover, by employing appropriate driving modulation, we show that a high-fidelity full quantum gate can be also realized, in which the initial and final spin states are on a bare basis. Our work provides a promising scheme for realizing high-fidelity quantum information processing.

In superconducting quantum circuits (SQCs), chiral routing quantum information is often realized with the ferrite circulators, which are usually bulky, lossy and require strong magnetic fields. To overcome those problems, we propose a novel method to realize chiral quantum networks by exploiting giant atom effects in SQC platforms. By assuming each coupling point being modulated with time, the interaction becomes momentum-dependent, and giant atoms will chirally emit photons due to interference effects. The chiral factor can approach 1, and both the emission direction and rate can be freely tuned by the modulating signals. We demonstrate that a high-fidelity state transfer between remote giant atoms can be realized. Our proposal can be integrated on the superconducting chip easily, and has the potential to work as a tunable toolbox for quantum information processing in future chiral quantum networks., Comment: 18 pages; 10 figures

Clean water scarcity is still an intense, prolonged global issue that needs to be resolved urgently. The solar steam generation has shown great potential with a high energy conversion efficiency for clean water production from seawater and wastewater. However, the high evaporation rate of water cannot be preserved due to the inevitable fouling of solar absorbers. Herein, a self-floatable and super hydrophilic solar-driven steam generator composed of activated carbon coated melamine foam (ACM). The deposited ACM photothermal layer exhibits outstanding solar absorption (92%) and an efficient evaporation rate of 1.27 kg m

Clean water scarcity is still an intense, prolonged global issue that needs to be resolved urgently. The solar steam generation has shown great potential with a high energy conversion efficiency for clean water production from seawater and wastewater. However, the high evaporation rate of water cannot be preserved due to the inevitable fouling of solar absorbers. Herein, a self-floatable and super hydrophilic solar-driven steam generator composed of activated carbon coated melamine foam (ACM). The deposited ACM photothermal layer exhibits outstanding solar absorption (92%) and an efficient evaporation rate of 1.27 kg m&minus, 2 h&minus, 1, along with excellent photothermal conversion efficiency (80%) as compared to commercially available primitive solar stills. The open porous assembly of melamine foam equipped with 80% flexibility (0.8 MPa) enabled smooth water transport and sustain heat accumulation within the matrix. The thermal insulation of ACM is 10 times greater than pure water. Moreover, open porous assembly of designed solar-powered steam generator rejects salt ions as well as volatile organic compounds efficiently. The low-cost and facile fabrication of photothermal based water production presents a potential solution to single step drinking water supply from various resources of the sea, the lakes and mixtures of emulsified oil and industrial wastewater.

The circuit quantum acoustodynamics which are studied in hybrid quantum system composed by artificial atoms and surface acoustic waves (SAWs) have drawn a lot of attention when exploring the nonclassical properties of phonons. In this paper, we propose a hybrid system for indirect coupling between multiple SAW resonators via auxiliary transmons. First, by eliminating the qubit degrees of freedom, the energy exchange between two SAW resonators can be observed. In the dispersive regime and suitable rotating frame, Fock state transition and entanglement can be realized between two SAW resonators. Second, by treating transmon as a qutrit and applying a classical driving for qutrit, the correlated phonon pairs between two SAW resonators will be detected. Moreover, by replacing the SAW resonators with acoustic-wave pumps, the acoustically induced transparency phenomenon is realized in our system. The transmon qutrit is potential to use as a switch for propagating acoustic waves, allowing the acoustic waves to be transmitted or backscattered.

The Himalaya is located in the southwest margin of the Tibetan Plateau. The region is of special interest for glacio-climatological research as it is influenced by both the continental climate of Central Asia and The Indian Monsoon system. Despite its large area covered by glaciers, detail glacier inventory data are not yet available for the entire Himalaya. The study presents spatial patterns in glacier area in the entire Himalaya are multiple spatial scales. We combined Landsat TM/ETM+/OLI from 1990 to 2015 and ASTER GEDM (30 m). In the years around 1990 the whole mountain range contained about 12211 glaciers covering an area of 23229.27 km2, while the ice on south slope covered 14451.25 km2. Glaciers are mainly distributed in the western of the Himalaya with an area of 11551.69 km2 and the minimum is the eastern. The elevation of glacier mainly distributed at 4,800∼6,200 m a.s.l. with an area percent of approximately 84 % in 1990. The largest number and ice cover of glaciers is hanging glacier and valley glacier, respectively. The number of debris-covered glaciers is relatively small, whereas covers an area of about 44.21 % in 1990. The glacier decreased by 10.99 % and this recession has accelerated from 1990 to 2015. The average annual shrinkage rate of the glaciers on the north slope (0.54 % a−1) is greater than that on the south slope (0.38 % a−1). Glacier decreased in the debris-covered glaciers and debris-free glaciers, and the area loss for the first is about 15.56 % and 5.22 % for the latter during 1990–2015, which showed that the moraine in the Himalaya can inhibit the ablation of glaciers to some extent.

We propose tunable chiral bound states in a system composed of superconducting giant atoms and a Josephson photonic-crystal waveguide (PCW), with no analog in other quantum setups. The chiral bound states arise due to interference in the nonlocal coupling of a giant atom to multiple points of the waveguide. The chirality can be tuned by changing either the atom-waveguide coupling or the external bias of the PCW. Furthermore, the chiral bound states can induce directional dipole-dipole interactions between multiple giant atoms coupling to the same waveguide. Our proposal is ready to be implemented in experiments with superconducting circuits, where it can be used as a tunable toolbox to realize topological phase transitions and quantum simulations., Comment: 27 pages, 17 figures

This study aimed to investigate whether exosomes secreted by mouse GATA-4-expressing bone marrow mesenchymal stem cells (BMSCs) could induce BMSC differentiation into myocyte precursors, decrease cardiomyocyte apoptosis, and improve cardiac function following myocardial infarction (MI). BMSCs were transduced with a lentivirus carrying a doxycycline (DOX)-inducible GATA-4 or control lentivirus, and secreted exosomes from these BMSCs were collected and co-cultured with BMSCs or cardiomyocytes under hypoxic and serum free conditions. Furthermore, exosomes were injected into mice 48 h after MI. Cardiac function was evaluated by echocardiography at 48, 72, and 96 h after exosome treatment. Quantitative PCR showed that co-culture of BMSCs with GATA-4-BMSC exosomes increased cardiomyocyte-related marker expression. Co-culture of GATA-4-BMSC exosomes with cardiomyocytes in anoxic conditions decreased apoptosis as detected by flow cytometry. Injection of GATA-4-BMSC exosomes in mice 48 h after MI increased cardiac function over the next 96 h; increased cardiac blood vessel density and number of c-kit-positive cells and decreased apoptotic cardiomyocyte cells were also observed. Differential expression of candidate differentiation- and apoptosis-related miRNAs and proteins that may mediate these effects was also identified. Exosomes isolated from GATA-4-expressing BMSCs induce differentiation of BMSCs into cardiomyocyte-like cells, decrease anoxia-induced cardiomyocyte apoptosis, and improve myocardial function after infarction.

Water scarcity in mass populated areas has become a major global threat to the survival and sustainability of community life on earth, which needs the prompt attention of technological leadership. Solar evaporation has emerged as a renewable energy resource and a novel technique for clean water production and wastewater treatment. Indeed, mounting a scalable solar evaporator including high evaporation efficiency and thermal management remains a significant challenge. Herein, we demonstrate a self-floatable, ecofriendly polypyrrole/wood sponge-based (PPy@WS) steam generator. The low-cost and easy to fabricate evaporator system consists of a single-step in situ polymerization of a 2-D (two-dimensional) hydrophilic wood sponge abundantly available for commercialization. The as-prepared PPy@WS solar evaporator exhibits excellent wettability and is super hydrophilic (contact angle ∼ 0), salt-resistant, and has an excellent light absorption of ∼94% due to omnidirectional diffusion reflection in PPy Nanoparticles (NPs). The capacity of the PPy@WS evaporator to absorb broadband solar radiation and convert it into thermal energy has enabled it to achieve excellent surface temperature (38.6 °C). The accumulated heat can generate vapors at the rate of 1.62 kg·m−2·h−1 along with 93% photothermal conversion efficiency under one sun (1 kW·m−2). Moreover, the presented prototype possesses the capability to be installed directly without the use of any complex protocol to purify seawater or sewage with an efficient rejection ratio of primary metal ions present in seawater (approximately 100%). This simple fabrication process with renewable polymer resources and photothermal materials can serve as a practical model towards high-performance solar evaporation technology for water-stressed communities in remote areas.

In this paper, the pulsation behavior of high-amplitude δ Scuti star GSC 4552-1498 was analyzed. Using the high-precision photometric data from the Transiting Exoplanet Survey Satellite, two new independent frequencies F1 = 22.6424(1) day−1 and F2 = 28.6803(5) day−1 were identified for this source, along with the fundamental one F = 17.9176(7) day−1, which was previously known. In addition, the classical O − C analysis was conducted to give a new ephemeris formula of BJDmax = T 0 + P × E = 2453321.534716(4) + 0.055811(0) × E. The O − C diagram reveals a continuous period increase, but the rate of (1/P)(dP/dt) = 1.11(3) × 10−7 yr−1 seems much larger (about hundreds) than predicted by evolution theories, which is long been noticed but not well understood, possibly related to nonlinear mode interaction. Based on frequency parameters (i.e., F, F1, and F2), a series of theoretical models were conducted by employing the stellar evolution code. It turns out that F1 should be a non-radial mode and F2 is the second overtone radial mode. Due to the mass–metallicity degeneracy, the stellar parameter of the star can however not be determined conclusively. We suggest high-resolution spectral observation is highly desired in the future to further constrain models. We note GSC 4552-1498 is located on the main sequence in the H-R diagram.

We investigate the nonequilibrium thermodynamics of a quenched XY spin chain with multi-spin interaction in a transverse field. The analytical expressions of both the average work and the relative entropy are obtained under different quenching parameters. The influences of the system parameters on the nonequilibrium thermodynamics are investigated. We find that at finite temperature the critical phenomenon induced by the multi-spin interaction and the external field can be revealed by the properties of the system nonequilibrium thermodynamics. In addition, our results indicate that the average work and the relative entropy can be used to detect both the existence and strength of the multi-spin interaction in the nonequlibrium system.

Gauge magnetic fields have a close relation to breaking time-reversal symmetry in condensed matter. In the present of the gauge fields, we might observe nonreciprocal and topological transport. Inspired by these, there is a growing effort to realize exotic transport phenomena in optical and acoustic systems. However, due to charge neutrality, realizing analog magnetic flux for phonons in nanoscale systems is still challenging in both theoretical and experimental studies. Here we propose a novel mechanism to generate synthetic magnetic field for phonon lattice by Floquet engineering auxiliary qubits. We find that, a longitudinal Floquet drive on the qubit will produce a resonant coupling between two detuned acoustic cavities. Specially, the phase encoded into the longitudinal drive can exactly be transformed into the phonon-phonon hopping. Our proposal is general and can be realized in various types of artificial hybrid quantum systems. Moreover, by taking surface-acoustic-wave (SAW) cavities for example, we propose how to generate synthetic magnetic flux for phonon transport. In the present of synthetic magnetic flux, the time-reversal symmetry will be broken, which allows to realize the circulator transport and analog Aharonov-Bohm effects for acoustic waves. Last, we demonstrate that our proposal can be scaled to simulate topological states of matter in quantum acoustodynamics system., 31 pages, 8 figures

In this paper, we study theoretically the optical response properties of the output field in a hybrid optomechanical system, in which a degenerate optical parametric amplifier (OPA) and a $$\varLambda $$ -type three-level atomic ensemble are placed in a driven optical cavity with a moving end mirror. We show that due to the presence of the OPA and the atomic medium, our proposal has the ability to exhibit the optical tristability and multiple optomechanically induced transparency (OMIT)-like effects. Moreover, the combined effects of optical amplification and OMIT-like as well as the tunable switch from slow-to-fast light can be realized by tuning the gain coefficient of the OPA and the phase of the field driving the OPA. In addition, the role of the OPA on the higher-order sideband generation has also been investigated. We find that the presence of the OPA contributes to the enhancement of the second-order sideband generation. These results provide a new way to engineer the hybrid optomechanical devices for applications in optical communications and signal processing.

Supplemental material, Supplementary_Figures_1-3 for Bone marrow mesenchymal stem cells overexpressing GATA-4 improve cardiac function following myocardial infarction by Ji-Gang He, Hong-Rong Li, Bei-Bei Li, Qiao-Li Xie, Dan Yan and Xue-Juan Wang in Perfusion

We theoretically propose an efficient method to realize electromagnetically induced transparency (EIT) in the microwave regime through a coupled system consisting of a flux qubit and a superconducting LC resonator. Driven by two appropriate microwave fields, the system will be trapped in the dark states. In our proposal, the control field of EIT is played by a second-order transfer rather than by a direct strong-pump field. In particular, we obtained conditions for electromagnetically induced transparency and Autler–Townes splitting in this composite system. Both theoretical and numerical results show that this EIT system benefits from the relatively long coherent time of the resonator. Since this whole system is artificial and tunable, our scheme may have potential applications in various domains.

We propose a four-state quantum key distribution (QKD) scheme using generalized measurement of nonorthogonal states, the maximum mutual information measurement strategy. Then, we analyze the eavesdropping process in intercept---resend and photon number splitting attack scenes. Our analysis shows that in the intercept---resend and photon number splitting attack eavesdropping scenes, our scheme is more secure than BB84 protocol and has higher key generation rate which may be applied to high-density QKD.

Experimental development of translational DNA nanomotors recently underwent a paradigm shift from bridge-burning monomers to symmetric dimers capable of truly sustainable motion. The focus of direction rectification is changed from carving the external landscape of a single particle to symmetry breaking from within a dimer. The symmetric dimer construction have the potential to facilitate efficient motors as friction, which is inevitable as a single particle moving in a viscous environment, may vanish for paired systems. However, creating high-performing nanomotors remains an open question from a fundamental physics perspective. Here, we present a realistic physical model for dimeric nanomotors that can be exactly solved to yield motor functions from experimentally accessible non-motor elements by mere physical laws—in a surprisingly rich mechanistic variety covering virtually all advanced dimeric DNA nanomotors invented to date plus major biological counterparts to a certain extent. The model exposes a high-performing regime with a sign of superlubricity for efficient motor operation. Reasonably simple for accurate treatments yet mechanistically telling, the present model has potential to evolve into a generic model to guide experimental optimization of DNA nanomotors toward low-dissipation operation.

Typical methods to decode a complex orbital-angular-momentum (OAM) spectrum suffer from issues such as a narrow OAM range, unstable interferometer, and long measuring time. In this Letter, we use a single-beam interferometer to measure the complex OAM spectrum with a single-pixel detector. The complex OAM spectrum ranging from − 10 to 10 can be measured in 11 ms with the fidelity approach of 97.0%, experimentally. Our approach allows one to characterize an unknown coherent field with any complex basis, e.g., the Laguerre–Gaussian (LG) basis is used for radial index spectrum measurement. Furthermore, single-pixel complex amplitude imaging based on the LG spectrum acquisition is presented, and the advantages in resolution and flexibility are demonstrated.

We theoretically investigate the optical response of an atom-assisted optomechanical system to a weak probe field at the presence of a strong coupling field and a time-dependent mechanical pump. We show that the phenomenon of optomechanically induced transparency can be converted to that of perfect absorption due to Jaynes-Cummings (J-C) coupling between a single-mode cavity field and a two-level atom, and the probe transmission strength can be further enhanced or suppressed by tuning amplitude and phase of the mechanical pump. Furthermore, phase dispersion of the transmission optical field is modified by controlling the J-C coupling strength and the applied pump, which provides an approach to tune group delay of the output probe field. Based on this hybrid optomechanical system, we can realize a conversion between slow and fast light effect by adjusting the J-C coupling strength. Moreover, the amplitude and phase of the mechanical pump as well as the coupling field amplitude can also be used to control the group delay. These results provide us an approach to manipulate light propagation, which will be helpful for quantum information processing.

The biomolecular motor kinesin uses chemical energy released from a fuel reaction to generate directional movement and produce mechanical work. The underlying physical mechanism is not fully understood yet. To analyze the energetics of the motor, we reconceptualize its chemomechanical cycle in terms of separate fuel reaction and work production processes and introduce a thermodynamic constraint to optimize the cycle. The model predicts that the load dependences of the motor’s velocity, stepping ratio, and dwell time are determined by the mechanical parameters of the motor–track system rather than the fuel reaction rate. This behavior is verified using reported experimental data from wild-type and elongated kinesins. The fuel reaction and work production processes indicate that kinesin is driven by switching between two chemical states, probably following a general pattern for molecular motors. The comparison with experimental data indicates that the fuel reaction processes are close to adiabatic, which is important for efficient operation of the motor. The model also suggests that a soft, short neck linker is important for the motor to maintain its load transport velocity.

We discuss level splitting and sideband transitions induced by a modulated coupling between a superconducting quantum circuit and a nanomechanical resonator. First, we show how to achieve an unconventional time-dependent longitudinal coupling between a flux (transmon) qubit and the resonator. Considering a sinusoidal modulation of the coupling strength, we find that a first-order sideband transition can be split into two. Moreover, under the driving of a red-detuned field, we discuss the optical response of the qubit for a resonant probe field. We show that level splitting induced by modulating this longitudinal coupling can enable two-color electromagnetically induced transparency (EIT), in addition to single-color EIT. In contrast to standard predictions of two-color EIT in atomic systems, we apply here only a single drive (control) field. The monochromatic modulation of the coupling strength is equivalent to employing two eigenfrequency-tunable mechanical resonators. Both drive-probe detuning for single-color EIT and the distance between transparent windows for two-color EIT, can be adjusted by tuning the modulation frequency of the coupling., 13 pages; 8 figures

Aortopulmonary septal defect, also known as the aortopulmonary window, is a rare congenital macrovascular malformation. This case involves a 9-year-old boy with aortopulmonary septal defect (type I combined with type IV). Before surgery, milrinone and alprostadil were used to counteract high lung pressure. Surgery was performed under cardiopulmonary bypass, following which the pulmonary pressure decreased. The aorta was cut, and the right pulmonary artery opening was connected with the main pulmonary artery septal defect using polyester patch. An internal tunnel was made, and the deformity correction was completed. The child exhibited normal postoperative recovery with no discomfort. A complex aortopulmonary window is a rare condition that can be treated successfully with appropriate preoperative and surgical management.

Determination of the orbital angular momentum (OAM) of vortex beams has been hotly discussed. We propose a new type of method to determine the orbital angular momentum of photons, filtering. We present an OAM filter scheme which consists of a cavity with a polarization-based Mach–Zehnder interferometer inside. Our scheme can purify the specific OAM with unitary efficiency theoretically without the pre-knowledge of the OAM spectrum of the input light. We also implemented a proof-of-principle experiment to demonstrate the feasibility of our scheme by cascading three interferometers. Our method offers a new way to determine the OAM spectrum of a light and this method can also be exploited to prepare the eigenstate of vortex beams.