Search

We have studied the Aharonov-Bohm flux-induced magnetic response of a disordered non-Hermitian ring. The disorder is introduced through an on-site quasiperiodic potential described by the Aubry-Andr\'{e}-Harper (AAH) model, incorporating a complex phase that renders the model non-Hermitian. Our findings reveal that this form of non-Hermiticity enhances the persistent current, without requiring hopping dimerization. We explore both non-interacting and interacting scenarios. In the former, we examine spinless fermions, while in the latter, we consider fermions with Hubbard interactions. The Non-Hermitian phase induces both the real and imaginary components of the current. We thoroughly analyze the energy eigenspectrum, ground state energy, and persistent current in both real and imaginary spaces for various system parameters. Our primary goal is to investigate the combined effects of non-Hermiticity and disorder strength on persistent currents. We find an enhancement in both the real and imaginary components of the persistent current with increasing disorder strength, as well as the non-Hermiticity, up to a critical value. Furthermore, we observe an enhancement in persistent current in the presence of Hubbard correlation. Our findings may provide a new route to get nontrivial characteristics in persistent current for a special type of non-Hermitian systems.

Quantum key distribution (QKD) enables secure key sharing between distant parties, with several protocols proven resilient against conventional eavesdropping strategies. Here, we introduce a new attack scenario where an eavesdropper, Eve, exploits a quantum switch using the indefinite causal order to intercept and manipulate quantum communication channel. Using multiple metrics such as the information gain, mutual information, and Bell violation, we demonstrate that the presence of a quantum switch significantly compromises QKD security. Our results highlight a previously overlooked vulnerability, emphasizing the need for countermeasures against quantum-controlled adversarial strategies.

Given the initial and final states of a quantum system, the speed of transportation of state vector in the projective Hilbert space governs the quantum speed limit. Here, we ask the question what happens to the quantum speed limit under continuous measurement process. We model the continuous measurement process by a non-Hermitian Hamiltonian which keeps the evolution of the system Schr{\"o}dinger-like even under the process of measurement. Using this specific measurement model, we prove that under continuous measurement, the speed of transportation of a quantum system tends to zero. Interestingly, we also find that for small time scale, there is an enhancement of quantum speed even if the measurement strength is finite. Our findings can have applications in quantum computing and quantum control where dynamics is governed by both unitary and measurement processes., Comment: 7 pages, 3 figures. Comments are welcome

Grover's quantum search algorithm promises a quadratic speedup for unstructured search over its classical counterpart. But this advantage is gradually reduced with noise acting on the search space. In this article, we demonstrate that a quantum switch can act as a resource operation in mitigating the effect of the noise in the search space. In this scenario, fault-tolerant model quantum computing is costly. In addition to the noise modeled by a depolarizing channel, which coherently acts on the entire quantum register, such an error correction method can not be trivially implemented. We show that a quantum switch can significantly add value by reducing this error. In particular, we propose two frameworks for the application of switches. In the first framework, we apply the superposition of channels' orders in the form of a switch and do a post-selection at every iteration of the applications of the Grover operator. In the second framework, we delay the post-selection until the very end. In other words, if we want to look at the switch's action at the kth step, we already have k-1 post-selection measurements in place for the first framework. In the second case, we only have a single measurement. The number of post selections is minimal in the second scenario, so its effect is more credited to the switch. It also gives a significant advantage regarding the success probability of Grover's algorithm. We take the success probability as the sole quantifier of the switch's action in diminishing the effect of noise in search space., Comment: 26 pages (14 + 12), 7 figures

The notions of predictability and visibility are essential in the mathematical formulation of wave particle duality. The work of Jakob and Bergou [Phys. Rev. A 76, 052107] generalises these notions for higher-dimensional quantum systems, which were initially defined for qubits, and subsequently proves a complementarity relation between predictability and visibility. By defining the single-party information content of a quantum system as the addition of predictability and visibility, and assuming that entanglement in a bipartite system in the form of concurrence mutually excludes the single-party information, the authors have proposed a complementarity relation between the concurrence and the single-party information content. We show that the information content of a quantum system defined by Jakob and Bergou is nothing but the Hilbert-Schmidt distance between the state of the quantum system of our consideration and the maximally mixed state. Motivated by the fact that the trace distance is a good measure of distance as compared to the Hilbert-Schmidt distance from the information theoretic point of view, we, in this work, define the information content of a quantum system as the trace distance between the quantum state and the maximally mixed state. We then employ the quantum Pinsker's inequality and the reverse Pinsker's inequality to derive a new complementarity and a reverse complementarity relation between the single-party information content and the entanglement present in a bipartite quantum system in a pure state. As a consequence of our findings, we show that for a bipartite system in a pure state, its entanglement and the predictabilities and visibilities associated with the subsystems cannot be arbitrarily small as well as arbitrarily large., Comment: 9 pages, no figures

The Grover search algorithm performs an unstructured search of a marked item in a database quadratically faster than classical algorithms and is shown to be optimal. Here, we show that if the search space is divided into two blocks with the local query operators and the global operators satisfy certain condition, then it is possible to achieve an improvement of bi-quadratic speed-up. Furthermore, we investigate the bi-quadratic speed-up in the presence of noise and show that it can tolerate noisy scenario. This may have potential applications for diverse fields, including database searching, and optimization, where efficient search algorithms play a pivotal role in solving complex computational problems.

The traditional quantum speed limits are not attainable for many physical processes, as they tend to be loose and fail to determine the exact time taken by quantum systems to evolve. To address this, we derive exact quantum speed limits for the unitary dynamics of pure-state quantum system that outperform the existing quantum speed limits. Using these exact quantum speed limits, we can precisely estimate the evolution time for two- and higher-dimensional quantum systems. Additionally, for both finite- and infinite-dimensional quantum systems, we derive an improved Mandelstam-Tamm bound for pure states and show that this bound always saturates for any unitary generated by self-inverse Hamiltonians. Furthermore, we show that our speed limits establish an upper bound on the quantum computational circuit complexity. These results will have a significant impact on our understanding of quantum physics as well as rapidly developing quantum technologies, such as quantum computing, quantum control and quantum thermal machines., Comment: 9 pages, no figure, added new results and example, Comments are welcome!

We investigate whether it is possible to teleport the coherence of an unknown quantum state from Alice to Bob by communicating a lesser number of classical bits in comparison to what is required for teleporting an unknown quantum state. We find that we cannot achieve perfect teleportation of coherence with one bit of classical communication for an arbitrary qubit. However, we find that if the qubit is partially known, i.e., chosen from the equatorial and polar circles of the Bloch sphere, then teleportation of coherence is possible with the transfer of one cbit of information when we have maximally entangled states as a shared resource. In the case of the resource being a non-maximally entangled state, we can teleport the coherence with a certain probability of success. In a general teleportation protocol for coherence, we derive a compact formula for the final state at Bob's lab in terms of the composition of the completely positive maps corresponding to the shared resource state and joint POVM performed by Alice on her qubit and the unknown state. Using this formula, we show that teleportation of the coherence of a partially known state with real matrix elements is possible perfectly with the help of a maximally entangled state as a resource. Furthermore, we explore the teleportation of coherence with the Werner states and show that even when the Werner states become separable, the amount of teleported coherence is non-zero, implying the possibility of teleportation of coherence without entanglement., Comment: 10 pages, no figures

Quantum entanglement for multiparty system has a unique feature when it comes to sharing its property among various subsystems. This is famously stated as the monogamy of entanglement. The traditional monogamy of concurrence for tripartite system was proved in a sum form. Recently, it was found that concurrence also respects a monogamy in the product form. Here, we prove a tight monogamy relation in the product form for the concurrence of pure tripartite systems. We illustrate our relation with several examples, including the canonical three qubit states, where this monogamy relation is saturated., Comment: 6 pages, 4figures

Here, we propose a novel method for representation of general spin systems using Restricted Boltzmann Machine with Softmax Regression (SRBM) that follows the probability distribution of the training data. SRBM training is performed using stochastic reconfiguration method to find approximate representation of many body wave functions. We have shown that proposed SRBM technique performs very well and achieves the trial wave function, in a numerically more efficient way, which is in good agreement with the theoretical prediction. We demonstrated that the prediction of the trial wave function through SRBM becomes more accurate as one increases the number of hidden units. We evaluated the accuracy of our method by studying the spin-1/2 quantum systems with softmax RBM which shows good accordance with the Exact Diagonalization(ED). We have also compared the energies of spin chains of a few spin multiplicities($1, 3/2$ and $2$) with ED and DMRG results., Comment: Incomplete work and no further progress along this direction

We consider a scenario of remote state preparation (RSP) of qubits in the context of sequential network scenario. A single copy of an entangled state is shared between Alice on one side, and several Bobs on the other, who sequentially perform unsharp single-particle measurements in order to prepare a specific state. In the given scenario without any shared randomness between the various Bobs, we first determine the classical bound of fidelity for the preparation of remote states by the Bobs. We then show that there can be at most 6 number of Bobs who can sequentially and independently prepare the remote qubit state in Alice's lab with fidelity exceeding the classical bound in the presence of shared quantum correlations. The upper bound is achieved when the singlet state is initially shared between Alice and the first Bob and every Bob prepares a state chosen from the equatorial circle of the Bloch sphere. Then we introduce a new RSP protocol for non-equatorial ensemble of states. The maximum number of Bobs starts to decrease from six when either the choice of remote states is shifted from the equatorial circle towards the poles of the Bloch sphere, or when the initial state shifts towards non-maximally entangled pure and mixed states., Comment: 41 pages, 9 figures, 6 tables

A deeply rooted view in classical and quantum information is that "information is physical", i.e., to store and process information, we need a physical body. Here we ask whether quantum information can remain without a physical body. We answer this question in the affirmative, i.e., we argue that quantum information can exist without a physical body in volatile form. We introduce the notion of the volatility of quantum information and show that indeed the conditions for it are naturally satisfied in the quantum teleportation protocol. We argue that even if special relativity principles are not assumed, it is possible to make quantum information volatile. We also discuss the classical limit of the phenomenon, as well as the multiparty scenario., Comment: 6 pages, no figures

Although there are enormous numbers of high-temperature thermoelectric materials present, designing a near-room-temperature especially n-type thermoelectric material with high zT is extremely challenging. Generally, pristine Ag2Se exhibits unusual low thermal conductivity along with high electrical conductivity and Seebeck coefficient, which leads to high thermoelectric performance (n-type) at room temperature. Herein, we report a pseudoternary phase, Ag2Se0.5Te0.25S0.25, which shows improved thermoelectric performance (zT ~ 2.1 at 400 K). Density functional theory reveals that the Rashba type of spin-dependent band spitting originated because of Te-doping, enhancing carrier mobility. Using density functional perturbation theory, we hereby realize that the intrinsic carrier mobility is not only controlled by carrier effective mass, neither deformation potential theory, instead it is substantially limited by longitudinal optical phonon scattering. In fact, locally off-centered S atoms and rising configurational entropy via substitution of Te and S atoms in Ag2Se significantly reduce the lattice thermal conductivity (klat ~ 0.34 at 400 K). In order to accurately obtain electrical as well as thermal transport coefficient, we adopt deformation potential theory based on Boltzmann transport formalism. The combined consequence of the Rashba effect coupled with configurational entropy synergistically results in such high thermoelectric performance with the development of new n-type thermoelectric material working at the near-room-temperature regime.

Over the last 5 years, UVIT has completed observations of more than 500 proposals with ~ 800 unique pointings. In addition, regular planned monitoring observations have been made and from their analysis various key parameters related to in orbit performance of UVIT have been quantified. The sensitivities of the UV channels have remained steady indicating no effect of potential molecular contamination confirming the adequacy of all the protocols implemented for avoiding contamination. The quality of the PSF through the years confirms adequacy of thermal control measures. The early calibrations obtained during the Performance Verification (PV) phase have been further revised for more subtle effects. These include flat fields and detector distortions with greater precision. The operations of UVIT have also evolved through in orbit experience, e.g. tweaking of operational sequencing, protocol for recovery from bright object detection (BOD) shutdowns, parameters for BOD thresholds, etc. Finally, some effects of charged particle hits on electronics led to opimised strategy for regular resetting. The Near-UV channel was lost in one of such operations. All the above in-orbit experiences are presented here., Comment: Accepted for publication in Journal of Astrophysics & Astronomy, 11 pages, 10 figures, 1 table

We have considered and alternating Heisenberg spin chain with nearest-neighbor ($J_1$), next-nearest neighbor ($J_2$) antiferromagnetic couplings along with z-component of the Dzyaloshinskii-Moriya(DM) ($D_z$) interactions. The Hamiltonian has been studied using (a) Linear Spin-Wave Theory(LSWT) and (b) Density Matrix Renormalization Group (DMRG). The system had been reported earlier as a classical ferrimagnet only when nearest neighbor exchange interactions are present. Both the antiferromagnetic next-nearest neighbor interactions and DM interactions introduce strong quantum fluctuations and due to which all the signatures of ferrimagnetism vanishes. We find that the nonzero $J_2$ introduces strong quantum fluctuations in each of the spin sites due to which the z-components of both spin-1 and spin-1/2 sites average out to be zero. The ground state becomes a singlet. The presence of $J_1$ along with $D_z$ introduces a short range order but develops long range order along the XY plane. $J_1$ along with $J_2$ induces competing phases with structure factor showing sharp and wide peaks, at two different angles reflecting the spin spiral structure locally as well as in the underlying lattice. Interestingly, we find that the $D_z$ term removes the local spin spiral structure in z-direction, while developing a spiral order in the XY plane.

Quantum mechanical perturbative expressions for second order dynamical magnetoelectric (ME) susceptibilities have been derived and calculated for a small molecular system using the Hubbard Hamiltonian with SU(2) symmetry breaking in the form of spin-orbit coupling (SOC) or spin-phonon coupling. These susceptibilities will have signatures in second harmonic generation spectra. We show that SU(2) symmetry breaking is the key to generate these susceptibilities. We have calculated these ME coefficients by solving the Hamiltonian for low lying excited states using Lanczos method. Varying the Hubbard term along with SOC strength, we find spin and charge and both spin-charge dominated spectra of dynamical ME coefficients. We have shown that intensities of the peaks in the spectra are highest when the magnitudes of Hubbard term and SOC coupling term are in similar range., Comment: 5 pages, 6 figures

Quantum measurement not only can destroy coherence but also can create it. Here, we estimate the maximum amount of coherence, one can create under a complete non-selective measurement process. For our analysis, we consider projective as well as POVM measurements. Based on our observations, we characterize the measurement processes into two categories, namely, the measurements with the ability to induce coherence and the ones without this ability. Our findings also suggest that the more POVM elements present in a measurement that acts on the quantum system, the less will be its coherence creating ability. We also introduce the notion of raw coherence in the POVMs that helps to create quantum coherence. Finally, we find a trade-off relation between the coherence creation, entanglement generation between system and apparatus, and the mixedness of the system in a general measurement setup., Comment: 8 pages, 4 figures, updated manuscript, and one new author, Gautam Sharma, added

Weakly coupled molecular junctions are an active and important field of research as they exhibit various non-linear transport phenomena. We have investigated the carrier transport through weakly coupled B2C2N2H6 molecules using quantum many-body approach coupled with kinetic (master) equations. Interestingly, various types of non-linear current-voltage characteristics, such as, negative differential conductance (NDC), rectifications, Coulomb staircase, which is the hallmark of multistate transport devices, have been obtained. The source-drain voltage induced change in the occupation probabilities of low-lying many-body states which are different in nature towards carrier transport, directly control the net current flowing through the molecular junctions. We further investigate the effect of different kinds of perturbations such as gate voltage and perpendicular magnetic field, over carrier-flow through this molecular bridge. Interestingly, we find that depending on the strength of the applied perturbating field, several phenomena, such as switching off of current, suppression of NDC appears in the devices. Fundamentally, this applied perturbations modifies both the site charge density as well as occupation probabilities of transport active channels, resulting in a significant alteration in transport behavior of this molecular junction.

Quantum State Tomography (QST) has been the traditional method for characterization of an unknown state. Recently, many direct measurement methods have been implemented to reconstruct the state in a resource efficient way. In this letter, we present an interferometric method, in which, any qubit state, whether mixed or pure, can be inferred from the visibility, phase shift and average intensity of an interference pattern using a single shot measurement -- hence, we call it Quantum State Interferography. This provides us with a "black box" approach to quantum state estimation, wherein, between the incidence of the photon and extraction of state information, we are not changing any conditions within the set-up, thus giving us a true single shot estimation of the quantum state. In contrast, standard QST requires at least two measurements for pure state qubit and at least three measurements for mixed state qubit reconstruction. We then go on to show that QSI is more resource efficient than QST for quantification of entanglement in pure bipartite qubits. We experimentally implement our method with high fidelity using the polarisation degree of freedom of light. An extension of the scheme to pure states involving $d-1$ interferograms for $d$-dimensional systems is also presented. Thus, the scaling gain is even more dramatic in the qudit scenario for our method where in contrast, standard QST, without any assumptions, scales roughly as $d^2$., Comment: version to appear in Physical Review Letters

Results of the initial calibration of the Ultra-Violet Imaging Telescope (UVIT) were reported earlier by Tandon et al. (2017). The results reported earlier were based on the ground calibration as well as the first observations in orbit. Some additional data from the ground calibration and data from more in-orbit observations have been used to improve the results. In particular, extensive new data from in-orbit observations have been used to obtain (a) new photometric calibration which includes (i) zero-points (ii) flat fields (iii) saturation, (b) sensitivity variations (c) spectral calibration for the near Ultra Violet (NUV; 2000 - 3000 Angstroms) and far Ultra-Violet (FUV; 1300 - 1800 Angstroms) gratings, (d) point spread function and (e) astrometric calibration which included distortion. Data acquired over the last three years show continued good performance of UVIT with no reduction in sensitivity in both the UV channels., Comment: 15 pages, 8 figures, Accepted for publication in Astronomical Journal

Quantum states that possess negative conditional von Neumann entropy provide quantum advantage in several information-theoretic protocols including superdense coding, state merging, distributed private randomness distillation and one-way entanglement distillation. While entanglement is an important resource, only a subset of entangled states have negative conditional von Neumann entropy. Despite this utility, a proper resource theory for conditional von Neumann entropy has not been developed, unlike that of entanglement. We pave the way for such a resource theory by characterizing the class of free states (density matrices having non-negative conditional von Neumann entropy) as convex and compact. This allows us to prove the existence of a Hermitian operator (a witness) for the detection of states having negative conditional entropy for bipartite systems in arbitrary dimensions. We construct a family of such witnesses and prove that the expectation value of any of them in a state is an upper bound to the conditional entropy of the state. We pose the problem of obtaining a tight upper bound to the set of conditional entropies of states in which an operator gives the same expectation value as a convex optimization problem. We solve it numerically for a two qubit case and find that this enhances the usefulness of our witnesses. We also find that for a particular witness, the estimated tight upper bound matches the value of conditional entropy for Werner states. We explicate the utility of our work in the detection of useful states in the above-mentioned protocols., Comment: Accepted for publication in Physical Review A

We propose a new measure of relative incompatibility for a quantum system with respect to two non-commuting observables, and call it quantumness of relative incompatibility. In case of a classical state, order of observation is inconsequential, hence probability distribution of outcomes of any observable remains undisturbed. We define relative entropy of the two marginal probability distributions as a measure of quantumness in the state, which is revealed only in presence of two non-commuting observables. Like all other measures, we show that the proposed measure satisfies some basic axioms. Also, we find that this measure depicts complementarity with quantum coherence. The relation is more vivid when we choose one of the observables in such a way that its eigen basis matches with the basis in which the coherence is measured. Our result indicates that the quantumness in a single system is still an interesting question to explore and there can be an inherent feature of the state which manifests beyond the idea of quantum coherence., Comment: 7 pages, 4 figures

SIGNALS, the Star formation, Ionized Gas, and Nebular Abundances Legacy Survey, is a large observing program designed to investigate massive star formation and HII regions in a sample of local extended galaxies. The program will use the imaging Fourier transform spectrograph SITELLE at the Canada-France-Hawaii Telescope. Over 355 hours (54.7 nights) have been allocated beginning in fall 2018 for eight consecutive semesters. Once completed, SIGNALS will provide a statistically reliable laboratory to investigate massive star formation, including over 50 000 resolved HII regions : the largest, most complete, and homogeneous database of spectroscopically and spatially resolved extragalactic HII regions ever assembled. For each field observed, three datacubes covering the spectral bands of the filters SN1 (363 -386 nm), SN2 (482 - 513 nm), and SN3 (647 - 685 nm) are gathered. The spectral resolution selected for each spectral band is 1000, 1000, and 5000, respectively. As defined, the project sample will facilitate the study of small-scale nebular physics and many other phenomena linked to star formation at a mean spatial resolution of 20 pc. This survey also has considerable legacy value for additional topics including planetary nebulae, diffuse ionized gas, andsupernova remnants. The purpose of this paper is to present a general outlook of the survey, notably the observing strategy, galaxy sample, and science requirements., Comment: 19 pages, 14 figures, submitted to MNRAS

We report ab-initio calculations of the phonon dispersion relation on the bulk and single layer of SnO and PbO. We identify Raman active modes and infrared active modes at the zone center {\Gamma} point. In agreement with experimental observations of Raman spectroscopy measurement, we find that A1g mode is higher in frequency than that of Eg mode. Moreover, the reason behind the shift of A2u mode to higher frequency for monolayer of both SnO and PbO is revealed from our calculations. We also find that long-range Coulomb interaction enhances the dielectric constant and Born effective charges in bulk SnO and bulk PbO, compared to their monolayer. Here, we observe avoided crossing or Landau degeneracy between longitudinal acoustics (LA) and low energetic transverse optical (TO) modes in bulk form of both SnO and PbO. Additionally, monolayer SnO also shows low energetic Raman modes (Eg and A1g) of same frequency as bulk. As a result, we notice avoided crossing between LA and TO modes in monolayer SnO. Interestingly, higher Born effective charge and low dielectric constant enhances self-force constants and the interatomic force constants (IFCs) between the M-O bonds. The enhanced force constants give rise to higher vibrational frequency of phonon modes for monolayer PbO. Our studies reveal that due to avoided crossing between two degenerate bands, the phonon dispersion near high symmetry X point lowers specific heat and vibrational entropy in bulk SnO, bulk PbO and only in monolayer SnO upto temperature 150 K. Moreover, the large mass difference between Pb and Oxygen atoms and absence of interlayer van der Waal interactions give rise to high phonon vibration which reduces the occurrence of band crossing between two degenerate energy levels. The absence of avoided crossing leads higher specific heat and vibrational entropy in monolayer PbO at low temperatures.

Motivated by recent experiments in fermionic polar gases, we study the non-equilibrium dynamics of two-component dipolar fermions subject to a quasiperiodic potential. We investigate the localization of charge and spin degrees of freedom time evolving with a long-range spin-SU(2) symmetric fermionic Hamiltonian, by calculating experimentally accessible dynamical observables. To study the non-equilibrium dynamics, we start the time evolution with two initial states at half-filling: (i) product state with doublons $|\uparrow \downarrow 0 \uparrow \downarrow 0 \uparrow \downarrow 0 \uparrow \downarrow 0 \uparrow \downarrow \rangle$ and (ii) product state with singlons $|\uparrow \ \downarrow \ \uparrow \ \downarrow \ \uparrow \ \downarrow \ \uparrow \ \downarrow \ \uparrow \ \downarrow \ \rangle$. We carried out the real-time evolution via the fermionic Hamiltonian using exact diagonalization(ED) and the time-dependent variational principle (TDVP) for finite Matrix product states(MPSs), within experimentally relevant time scales. For the product state with doublons, we observe a delocalized to localized phase transition varying disorder strengths, by monitoring the decay of charge imbalance with time. For the long-range interacting Hamiltonian of our focus, and in the presence of strong enough disorder, starting the time evolution with singlons we find a strong reduction in the spin delocalization, contrary to results of previous studies using the disordered short-range (on-site) Hubbard model with SU(2) symmetry. Our predictions for localization of both charge and spin should be observable in ultra-cold experiments with fermionic dipolar atoms subject to a quasiperiodic potential., Comment: 16 pages and 14 Figures

Quantum theory allows direct measurement of the average of a non-Hermitian operator using the weak value of the positive semidefinite part of the non-Hermitian operator. Here, we experimentally demonstrate the measurement of weak value and average of non-Hermitian operators by a novel interferometric technique. Our scheme is unique as we can directly obtain the weak value from the interference visibility and the phase shift in a Mach Zehnder interferometer without using any weak measurement or post selection. Both the experiments discussed here were performed with laser sources, but the results would be the same with average statistics of single photon experiments. Thus, the present experiment opens up the novel possibility of measuring weak value and the average value of non-Hermitian operator without weak interaction and post-selection, which can have several technological applications., Comment: 9 pages, 11 figures (v2: minor typographical errors corrected)

We derive generalized charge energy rate equations for organic solids and biomolecular aggregates, even when these are dynamically disordered. These equations suggest that the transport in such cases rely on both drift and diffusion phenomena. The presence of disorder and field effects makes the equations nonlinear and together with cooperativity, these enhance the charge and energy transport. The generalized drift diffusion expression connects the adiabatic band and nonadiabatic hopping transport mechanisms, well suited for any complex organic semiconductors or assemblies of bio molecular systems. Here we have proposed donor-acceptor (DA) reaction state model, which examines the probability of charge transfer and the rate between two distinct transition state identities. From our analytical equations, we suggest that charge and energy transport property in DA states can be tuned by only a single parameter, i.e., the chemical potential. Importantly, we find the non-equilibrium assisted drift-diffusion transport at non- steady state regime in 2D and 3D semiconducting devices. The numerical results clearly support our unified analytical equations, which goes beyond Einstein's diffusion law even in quasi- equilibrium cases., Comment: 19 pages

We investigate the coherence of quantum channels using the Choi-Jamio\l{}kowski isomorphism. The relation between the coherence and the purity of the channel respects a duality relation. It characterizes the allowed values of coherence when the channel has certain purity. This duality has been depicted via the Coherence-Purity (Co-Pu) diagrams. In particular, we study the quantum coherence of the unital and non-unital qubit channels and find out the allowed region of coherence for a fixed purity. We also study coherence of different incoherent channels, namely, incoherent operation (IO), strictly incoherent operation (SIO), physical incoherent operation (PIO) etc. Interestingly, we find that the allowed region for different incoherent operations maintain the relation $PIO\subset SIO \subset IO$. In fact, we find that if PIOs are coherence preserving operations (CPO), its coherence is zero otherwise it has unit coherence and unit purity. Interestingly, different kinds of qubit channels can be distinguished using the Co-Pu diagram. The unital channels generally do not create coherence whereas some nonunital can. All coherence breaking channels are shown to have zero coherence, whereas, this is not usually true for entanglement breaking channels. It turns out that the coherence preserving qubit channels have unit coherence. Although the coherence of the Choi matrix of the incoherent channels might have finite values, its subsystem contains no coherence. This indicates that the incoherent channels can either be unital or nonunital under some conditions., Comment: 11 pages, 7 figures. One result concerning Holevo quantity has been removed