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Alireza Bahrampour

Publications and source records attributed to Alireza Bahrampour.

16 recordsLinked to original sources

Parallel Data Processing in Quantum Machine Learning

We propose a Quantum Machine Learning (QML) framework that applies the core design principle of quantum algorithms-superposition, oracle, and interference-to accelerate training. Building on the structural analogy between feature extraction in foundational quantum algorithms and parameter optimization in QML, we reformulate the training process to leverage quantum parallelism: all training samples are encoded into a quantum superposition, processed through a parameterized quantum circuit, and classified via an interferometer module that implements quantum interference across the dataset. This architectural reformulation reduces the theoretical complexity of loss function evaluation from $O(N^{2})$ in conventional QML training to $O(N)$, where $N$ is the dataset size. Numerical simulations on multiple binary and multi-class classification datasets (with up to $N=128$ samples) demonstrate that our method achieves classification accuracies comparable to conventional circuits while reducing the number of quantum circuit executions per cost function evaluation from $N$ to 1. This represents a near $N$-fold reduction in quantum overhead per training iteration, reducing the required circuit executions without loss of accuracy. These results highlight the potential of quantum algorithmic design principles as a scalable pathway to efficient QML implementations.

quant-ph

Enhancing the security of coherent one-way quantum key distribution using CHSH correlations

The coherent one-way (COW) protocol is a quantum key distribution scheme that has attracted significant attention, leading to the development and commercialization of practical implementations. Despite this progress, the security of the COW protocol has remained a fundamental challenge since its introduction. Numerous studies have investigated its security, and several security proofs have been proposed over the years. More recently, a number of works have questioned the security of this protocol. In particular, one of the latest studies introduced an attack that severely limits the security of COW-QKD and reported a maximum secure distance of less than 20km. In this work, we introduce minimal alteration to the COW protocol that can enhance its security. Specifically, instead of monitoring the coherence between successive pulses, we propose to monitor quantum correlations through the violation of Bell inequalities. This approach enables the detection of a broader class of potential attacks. Our simulation results indicate that, by employing this method, the maximum secure distance of the protocol can be extended to approximately 259km.

quant-ph

Influence of Oscillating Magnetic Fields on the Electric Dipole Moment of Radical Pairs in Cryptochrome Based Magnetoreception

Radical pairs induced by light-driven reduction of cryptochrome protein constitute a spin dependent mechanism that is accompanied by an electric dipole moment and is found to be sensitive to external magnetic fields. In this research, to investigate for the further proof of such model, the simultaneous effect of the Earth's static magnetic field and the time-dependent magnetic field noise on the electric dipole moment of the radical pair has been studied within the quantum mechanical framework. The effect of the external magnetic field discussed in different angles regarding the Earth magnetic field within various frequencies and magnitudes. The sensitivity of the system behavior to the external magnetic field frequencies and magnitudes, vastly differs among the changes in the magnetic field angle to the Earth's static field. Furthermore, the sensitivity studied under the effect of the environmental noise. The relative spatial orientation of the two magnetic field components plays an important role in the time evolution of the electric dipole moment. Also, deeper discussions on specific relative orientations of the external magnetic fields, such as 24 degree, shows that the quantum model of radical pairs which is based on dipole moment, is in agreement with the results of the birds behavorial studies. These findings provide new insights into the sensitivity of the radical pair model to the combination of magnetic fields and may contribute to a comprehensive understanding of the phenomenon of magnetoreception and the advancement of bioinspired magnetic sensors.

physics.bio-ph

Quantum modeling of radical pair magnetic sensor based on electric dipole moment

Photoreduction of cryptochrome protein in the retina is a well-known mechanism of navigation of birds through the geomagnetic field, yet the biosignal nature of the mechanism remains unclear. The absorption of blue light by the flavin adenine dinucleotide (FAD) chromophore can alter the distribution of electrons in cryptochrome and create radical pairs with separated charges. In this study, the spin dynamics of electrons in the radical pair including its spin-orbit coupling were investigated by quantum mechanical modeling. Spin-orbit coupling is negligible relative to other terms and has no significant role in the dynamics. However, it engages the spatial states of the radical pair and make possible to study spatial related observables. Several interactions were considered in the presence of an external magnetic field, and the resulting electric dipole moment in cryptochrome was computed as the quantity emerging from this coupling. The computations show the induced electric dipole moment clearly depend on the characteristics of the applied magnetic field even after considering dissipative effects. In fact, our findings indicate that the radical pair in cryptochrome protein is a magnetic biosensor, in the sense that in the presence of the geomagnetic field, variations in spin states can influence its electric dipole moment, which may be interpreted via the bird as an orientation signal. The results can be used in the advancement of bio-inspired technologies which replicate animal magnetic sensitivity.

physics.bio-ph

Learning Hamiltonians for $O(1)$ Oracle-Query Quantum State Preparation

We propose a Hamiltonian-based quantum state preparation method implemented via a shallow parametrized quantum circuit. The approach learns the parameters of a diagonal Hamiltonian through a classical training phase, while the quantum circuit itself performs only fixed-depth Hamiltonian evolution and mixing operations. With oracle access to the learned Hamiltonian parameters, $N$ classical data values can be encoded into $n=\log_2{N}$ qubits using $O(1)$ quantum queries, shifting the overall computational cost to an $O(N\log{N})$ classical preprocessing stage. For structured datasets generated by an underlying function, oracle access can be avoided by expressing the Hamiltonian in the Walsh basis and retaining only a polynomial number of significant terms. In this regime, quantum state preparation is achieved in $\text{poly}(n)$ time using $\text{poly}(n)$ parameters, reaching infidelities on the order of $10^{-5}$. By restricting the Hamiltonian to one-local and two-local terms, the method naturally yields hardware-efficient circuits suitable for near-term quantum devices.

quant-ph

Development of Neural Network-Based Optimal Control Pulse Generator for Quantum Logic Gates Using the GRAPE Algorithm in NMR Quantum Computer

In this paper, we introduce a neural network to generate optimal control pulses for general single-qubit quantum logic gates, within a Nuclear Magnetic Resonance (NMR) quantum computer. By utilizing a neural network, we can efficiently implement any single-qubit quantum logic gates within a reasonable time scale. The network is trained by control pulses generated by the GRAPE algorithm, all starting from the same initial point. After implementing the network, we tested it using numerical simulations. Also, we present the results of applying Neural Network-generated pulses to a three-qubit benchtop NMR system and compare them with simulation outcomes. These numerical and experimental results showcase the precision of the Neural Network-generated pulses in executing the desired dynamics. Ultimately, by developing the neural network using the GRAPE algorithm, we discover the function that maps any single-qubit gate to its corresponding pulse shape. This model enables the real-time generation of arbitrary single-qubit pulses. When combined with the GRAPE-generated pulse for the CNOT gate, it creates a comprehensive and effective set of universal gates. This set can efficiently implement any algorithm in noisy intermediate-scale quantum computers (NISQ era), thereby enhancing the capabilities of quantum optimal control in this domain. Additionally, this approach can be extended to other quantum computer platforms with similar Hamiltonians.

quant-ph

Reducing the Number of Qubits from $n^2$ to $n\log_{2} (n)$ to Solve the Traveling Salesman Problem with Quantum Computers: A Proposal for Demonstrating Quantum Supremacy in the NISQ Era

In our pursuit of quantum supremacy during the NISQ era, this research introduces a novel approach rooted in the Quantum Approximate Optimization Algorithm (QAOA) framework to address the Traveling Salesman Problem (TSP). By strategically reducing the requisite qubit count from $n^2$ to $n\log_{2} (n)$, our QAOA-based algorithm not only contributes to the ongoing discourse on qubit efficiency but also demonstrates improved performance based on established metrics, underscoring its potential for achieving NISQ-era supremacy in solving real-world optimization challenges.

quant-ph

Single-photon generation at room temperature using molecular optomechanics in a hybrid photonic-plasmonic cavity

We propose a novel integrated structure for single photon generation at room temperature based on a molecular optomechanics system in a hybrid photonic-plasmonic cavity. The proposed structure comprises a single molecule within a plasmonic cavity, coupled to a 2D photonic crystal resonator. In this paper, we theoretically identify the ability of the scheme through calculation second order correlation function g^2 (0) for four different coupling regimes. We demonstrate the quantum paths and the destructive interference mechanism through the selection of efficient and preferred basis. Furthermore, we find that the unconventional photon blockade effects can occurs in the weak molecular optomechanics coupling. This structure holds the potential to serve as an integrated single-photon source for quantum networks at room temperature.

physics.optics

Long-distance high-fidelity continuous-variable quantum key distribution with non-Gaussian operations: An exact closed form solution

In this paper, we derive a closed form expression for the output state of a CV-QKD protocol in the presence of zero-photon catalysis (ZPC) and quantum scissor (QS). Then, based on this closed form solution, we use direct search algorithm to find the appropriate values of input state and QS parameters, which considerably enhance the range and the fidelity of a CV-QKD protocol. In the special case of pure loss channel, the largest range of the protocol is only 6.5% less than the fundamental limit of repeaterless quantum communication. In addition, examination of the protocol for different values of excess noise, reveals that their is a trade-off between range and fidelity, and high value of fidelity can be obtained at the cost of a slight reduction in protocol range.

quant-ph

Quantum Multiplication Algorithm Based on the Convolution Theorem

The problem of efficient multiplication of large numbers has been a long-standing challenge in classical computation and has been extensively studied for centuries. It appears that the existing classical algorithms are close to their theoretical limit and offer little room for further enhancement. However, with the advent of quantum computers and the need for quantum algorithms that can perform multiplication on quantum hardware, a new paradigm emerges. In this paper, inspired by convolution theorem and quantum amplitude amplification paradigm we propose a quantum algorithms for integer multiplication with time complexity $O(\sqrt{n}\log^2 n)$ which outperforms the best-known classical algorithm, the Harvey algorithm with time complexity of $O(n \log n)$. Unlike the Harvey algorithm, our algorithm does not have the restriction of being applicable solely to extremely large numbers, making it a versatile choice for a wide range of integer multiplication tasks. The paper also reviews the history and development of classical multiplication algorithms and motivates us to explore how quantum resources can provide new perspectives and possibilities for this fundamental problem.

quant-ph

Can the double-slit experiment distinguish between quantum interpretations?

Despite the astonishing successes of quantum mechanics, due to some fundamental problems such as the measurement problem and quantum arrival time problem, the predictions of the theory are in some cases not quite clear and unique. Especially, there are various predictions for the joint spatiotemporal distribution of particle detection events on a screen, which are derived from different formulations and interpretations of the quantum theory. Although the differences are typically small, our studies show that these predictions can be experimentally distinguished by an unconventional double-slit configuration, which is realizable using present-day single-atom interferometry. This experiment would enrich our understanding of the foundations of quantum mechanics.

quant-ph

An analogical model for the stationary black holes by the flow field of space-time fluid around a 3-dimensional point sink

Recent researches suggest an analogy between the theory of general relativity (GR) and fluid dynamics. As a result of this analogy, the Navier-Stokes equations and Einstein field equations are the same, and it is possible to study the properties of space-time by using fluid mechanics. In this paper, we present a new model to describe gravitational phenomena by an inviscid and compressible fluid called space-time fluid (STF). The analogy method is used to obtain the gravity field of both static and rotating masses from the flow field of STF around static and rotating point sinks. In addition, event horizons and the ergosphere of stationary black holes are defined based on our STF model. Then, we compare hydrodynamic forces exerted on a test particle with gravitational forces in the gravitoelectromagnetic approximation of the GR. As a natural consequence, it is shown that inertial and gravitational masses are equivalent in this analogy. Finally, using the aspect of fluid dynamics, Mach's principle, weak equivalence principle, and information discontinuity on the event horizon are discussed.

gr-qc

Continuous quantum clock with high precision and long recurrence time

Continuous clocks, i.e. the clocks that measure time in a continuous manner, are regarded as an essential component of sensing technology. Precision and recurrence time are two basic features of continuous clocks. In this paper, in the framework of quantum estimation theory various models for continuous quantum clocks are proposed, where all tools of quantum estimation theory are employed to seek the characteristics of clocks with high precision and long recurrence time. Then, in a resource-based approach, the performance of the proposed models is compared. It is shown that quantum clocks based on $n$ two-qubits system not only can have better precision than quantum clocks based on $2n$ one-qubit system but also support long recurrence time. Finally, it is shown that while employing the number of $n$ entangled qubits improves the precision of clocks by a factor of $1/\sqrt n $, it inevitably worsens the recurrence time of the clock.

quant-ph

Optimal exploitation of the resource in remote state preparation

Transmission efficiency (TE) of remote state preparation (RSP) with a shared quantum state and one bit of classical communication is considered. Following [B. Daki et al., Nat. Phys. 8, 666 (2012)], the encoding and decoding strategies of the protocol are restricted to the physically relevant classes of projective measurements and unitary operators, respectively. It is shown that contrary to the previous arguments, the quadratic fidelity as well as the linear fidelity could be a valid figure of merit to quantify the TE of RSP. Then, the TE of the protocol in terms of both linear and quadratic fidelities is evaluated in a fully optimized scenario which includes the maximization over the encoding parameters as well as a meaningful maximization over the decoding parameters. The results show that in this scenario, the TE scales with the sum of the two largest eigenvalues of the squared correlation matrix of the resource state that is zero only for product states. This approach successfully quantifies the performance of the protocol in terms of the resource state parameters and provides a means to compare the usefulness of any two resource states for RSP.

quant-ph

Confidential Continuous Variable Direct Communication Protocol by Using Fock-Coherent Entangled States

We propose a scheme for the secure direct communication based on the entangled phase-coherent states, which shows an elevated level of confidentiality. The protocol gives a simultaneous security control for every bit of transferred information. The security-check-per-bit is provided by sending an additional mode to prove the legitimate parties' authenticity. Other benefit include increased transfer rate, since a separate control sequences is unnecessary. We study the security of the scheme for both ideal and realistic quantum channel. The protocol shows a robust security and prepares 50% probability to detect the presence of the eavesdropper.

quant-ph

Effect of laser phase noise on the fidelity of optomechanical quantum memory

Optomechanical and electromechanical cavities have been widely used in quantum memories and quantum transducers. We theoretically investigate the robustness of opto(electro)-mechanical quan- tum memories against the noise of the control laser. By solving the Langevin equations and using the covariance matrix formalism in the presence of laser noise, the storing fidelity of Gaussian states is obtained. It is shown that, the destructive effect of phase noise is more significant in higher values of coupling laser amplitude and optomechanical coupling strength G. However, by further increasing coupling coefficient, the interaction time between photons and phonons decreases below the coherence time of laser frequency noise and the destructive effect of laser phase noise on the storing fidelity drops as well.

quant-ph