Hoshang Heydari
We construct a generalized controlled phased gate entangler for a multi-qubit state based on the geometrical structure of quantum systems. We also investigate relation between the generalized controlled phase construction of a quantum gate entangler and graph state for two-qubit and three-qubit states.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
继续探索
Faster Quantum Algorithm for Multiple Observables Estimation in Fermionic Problems
本文提出一种通用自适应QGE算法框架及其两种变体，实现费米系统集体性质估计的高效计算，相比现有算法在有限粒子数系统中提供二次加速。
An efficient and economical scheme is proposed for the perfect quantum teleportation of n-qubit non-maximally entangled state of generalized Bell-type. A Bell state is used as the quantum channel in the proposed scheme. It is also shown that the controlled teleportation of this n-qubit state can be achieved by using a GHZ state or a GHZ-like state as quantum channel. The proposed schemes are economical because for the perfect and controlled teleportation of n-qubit non-maximally entangled state of generalized Bell-type we only need a Bell state and a tripartite entangled state respectively. It…
We present a novel scheme for controlled quantum secure communication (CQSC) using GHZ-like state. In this scheme, a trusted controller assists the users for achieving secure transmission of data between them. The dense coding technique is exploited to increase the qubit efficiency and we show that the proposed scheme is immune against common eavesdropping attacks. We show how the method can be generalized to include N controllers using sets of GHZ-like states shared among the controllers and users. In this process entanglement swapping and single particle measurements are performed by the con…
It is shown that a realistic, controlled bidirectional remote state preparation is possible using a large class of entangled quantum states having a particular structure. Existing protocols of probabilistic, deterministic and joint remote state preparation are generalized to obtain the corresponding protocols of controlled bidirectional remote state preparation (CBRSP). A general way of incorporating the effects of two well known noise processes, the amplitude-damping and phase-damping noise, on the probabilistic CBRSP process is studied in detail by considering that noise only affects the tra…
Recently bidirectional controlled perfect teleportation using 5-qubit states are reported in (Int. J. Theor. Phys. (2013) DOI 10.1007/s10773-013-1484-8 and ibid, (2013) DOI 10.1007/s10773-012-1208-5). In this paper we have shown that there exists a class of 5-qubit quantum states that can be used for bidirectional controlled teleportation. Two out of the three reported cases are the special cases of the proposed class of 5-qubit quantum states and one of them is not strictly a case of controlled bidirectional quantum teleportation. Further, we have shown that one can in principle, construct in…
Based on the controlled order rearrange encryption (CORE) for quantum key distribution using EPR pairs[Fu.G.Deng and G.L.Long Phys.Rev.A68 (2003) 042315], we propose the generalized controlled order rearrangement encryption (GCORE) protocols of $N$ qubits and $N$ qutrits, concretely display them in the cases using 3-qubit, 2-qutrit maximally entangled basis states. We further indicate that our protocols will become safer with the increase of number of particles and dimensions. Moreover, we carry out the security analysis using quantum covariant cloning machine for the protocol using qutrits. A…
The SWAP gate plays a central role in network designs for qubit quantum computation. However, there is a view to generalize qubit quantum computing to higher dimensional quantum systems. In this paper we construct a generalized SWAP gate using only instances of the generalized controlled-NOT gate to cyclically permute the states of $d$ qudits for $d$ prime.
We present quantum networks for a n-qubit controlled gate C^{n-1}(U) which use a higher dimensional (qudit) ancilla as a catalyser. In its simplest form the network has only n two-particle gates (qubit-qudit) -- this is the minimum number of two-body interactions needed to couple all n+1 subsystems (n qubits plus one ancilla). This class of controlled gates includes the generalised Toffoli gate C^{n-1}(X) on n qubits, which plays an important role in several quantum algorithms and error correction. A particular example implementing this model is given by the dispersive limit of a generalised J…
Remote Implementation of Hidden or Partially Unknown Quantum Operators using Optimal Resources: A Generalized View
本文提出两种基于两量子比特最大纠缠态的协议，分别用于远程实现隐藏和部分未知单量子比特算符，并将其推广到受控、双向及循环等版本，证明贝尔态及其乘积即可完成任务，显著降低了量子资源需求。
We study universal quantum computation in the cavity quantum electrodynamics (CQED) framework exploiting two orthonormal two-photon generalized binomial states as qubit and dispersive interactions of Rydberg atoms with high-$Q$ cavities. We show that an arbitrary qubit state may be generated and that controlled-NOT and 1-qubit rotation gates can be realized via standard atom-cavity interactions.
We show that it is possible to control the trade-off between information gain and disturbance in generalized measurements of qudits by utilizing the programmable quantum processor. This universal quantum machine allows us to perform a generalized measurement on the initial state of the input qudit to construct a Husimi function of this state. The trade-off between the gain and the disturbance of the qudit is controlled by the initial state of ancillary system that acts as a program register for the quantum-information distributor. The trade-off fidelity does not depend on the initial state of …
Using the generalized Bell states and controlled not gates, we introduce an enatanglement-based quantum key distribution (QKD) of d-level states (qudits). In case of eavesdropping, Eve's information gain is zero and a quantum error rate of (d-1)/d is introduced in Bob's received qudits, so that for large d, comparison of only a tiny fraction of received qudits with the sent ones can detect the presence of Eve.
We provide several schemes to construct the continuous-variable SWAP gate and present a Hermitian generalized many-body continuous controlled^n-NOT gate. We introduce and study the hybrid controlled-NOT gate and controlled-SWAP gate, and physical realizations of them are discussed in trapped-ion systems. These continuous-variable and hybrid quantum gates may be used in the corresponding continuous-variable and hybrid quantum computations.
Optimizing a parameterized controlled gate using Free Quaternion Selection
本研究将自由四元数选择技术扩展应用于参数化广义受控门，提出局部最小化代价函数的优化算法，在多种量子优化任务中实现更高效优化、更强表达能力与更浅电路，还可推广优化粒子数守恒门以提升分子时间演化算符的量子编译效果。
The characteristic stretching and squeezing of chaotic motion is linearized within the finite number of phase space domains which subdivide a classical baker map. Tensor products of such maps are also chaotic, but a more interesting generalized baker map arises if the stacking orders for the factor maps are allowed to interact. These maps are readily quantized, in such a way that the stacking interaction is entirely attributed to primary qubits in each map, if each subsystem has power-of-two Hilbert space dimension. We here study the particular example of two baker maps that interact via a con…
Extending a previous result on the generation of two-photon generalized binomial field states, here we propose an efficient scheme to generate with high-fidelity, in a single-mode high-Q cavity, N-photon generalized binomial states with a maximum number of photons N>2. Besides their interest for classical-quantum border investigations, we discuss the applicative usage of these states in realizing universal quantum computation, describing in particular a scheme that performs a controlled-NOT gate by dispersive interaction with a control atom. We finally analyze the feasibility of the proposed s…
Efficient verification of the functioning of quantum devices is a key to the development of quantum technologies, but is a daunting task as the system size increases. Here we propose a simple and general framework for verifying unitary transformations that can be applied to both individual quantum gates and gate sets, including quantum circuits. This framework enables efficient verification of many important unitary transformations, including but not limited to all bipartite unitaries, Clifford unitaries, generalized controlled-$Z$ gates, generalized controlled-NOT gates, the controlled-SWAP g…
Controlled-Joint Remote Implementation of Operators and its Possible Generalization
本文提出受控联合远程实现任意酉算子的协议，利用四量子比特超纠缠态，在监督者控制下由两个用户联合实现，并推广至任意控制器和参与方数量，涵盖现有量子远程控制方案。
Entangling capability of coherently controlled quantum processes
该研究解析表征量子开关和时间翻转两种相干控制量子过程的纠缠能力，推导纠缠相关表达式，扩展分析至多种信道，揭示存在耗散时仍可生成最大纠缠，为相干控制量子过程的纠缠生成提供系统分析。
Doubling Efficiency of Hamiltonian Simulation via Generalized Quantum Signal Processing
本研究针对哈密顿量模拟成本问题，利用广义量子信号处理的最新成果，结合正反步骤控制成本接近简单受控操作的特性，实现模拟成本减半，提升了模拟效率。
We investigate minimal control power (MCP) for controlled dense coding defined by the channel capacity. We obtain MCPs for extended three-qubit Greenberger-Horne-Zeilinger (GHZ) states and generalized three-qubit $W$ states. Among those GHZ states, the standard GHZ state is found to maximize the MCP and so does the standard $W$ state among the $W$-type states. We find the lower and upper bounds of the MCP and show for pure states that the lower bound, zero, is achieved if and only if the three-qubit state is biseparable or fully separable. The upper bound is achieved only for the standard GHZ …
Construction of multi-particle entangled states and direct teleportation of N-(spin 1/2) particles are important areas of quantum information processing. A number of different schemes which have been presented already, address the problem through controlled teleportation. In this article, a criterion based on standard quantum statistical correlations employed in the many body virial expansions is used to determine maximum entanglement for a N-particle state. These states remain entangled through proper traces to states for a smaller number of particles and can be generalized for arbitrary numb…
Optical quantum memory with generalized time-reversible atom-light interactions
本文提出一种基于可控退相干的量子存储方案，将光与原子系综的时间可逆相互作用从弱场线性情形推广到强场非线性情形，并建立统一框架以涵盖受控可逆非均匀展宽和原子频率梳等不同实现方式。
We present a general scheme for multiparty-controlled teleportation of an arbitrary m-qudit ($d$-dimensional quantum system) state by using non-maximally entangled states as the quantum channel. The sender performs m generalized Bell-state measurements on her 2$m$ particles, the controllers take some single-particle measurements with the measuring basis $X_{d}$ and the receiver only need to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if he cooperates with all the controllers. All the parties can use some decoy photons to se…
We introduce the sudden variant (SNZ) of the Net Zero scheme realizing controlled-$Z$ (CZ) gates by baseband flux control of transmon frequency. SNZ CZ gates operate at the speed limit of transverse coupling between computational and non-computational states by maximizing intermediate leakage. The key advantage of SNZ is tuneup simplicity, owing to the regular structure of conditional phase and leakage as a function of two control parameters. We realize SNZ CZ gates in a multi-transmon processor, achieving $99.93\pm0.24\%$ fidelity and $0.10\pm0.02\%$ leakage. SNZ is compatible with scalable s…
Random quantum states and operations are of fundamental and practical interests. In this work, we investigate the entanglement properties of random hypergraph states, which generalize the notion of graph states by applying generalized controlled-phase gates on an initial reference product state. In particular, we study the two ensembles generated by random Controlled-Z(CZ) and Controlled-Controlled-Z(CCZ) gates, respectively. By applying tensor network representation and combinational counting, we analytically show that the average subsystem purity and entanglement entropy for the two ensemble…
We derive an encoded universality representation for a generalized anisotropic exchange Hamiltonian that contains cross-product terms in addition to the usual two-particle exchange terms. The recently developed algebraic approach is used to show that the minimal universality-generating encodings of one logical qubit are based on three physical qubits. We show how to generate both single- and two-qubit operations on the logical qubits, using suitably timed conjugating operations derived from analysis of the commutator algebra. The timing of the operations is seen to be crucial in allowing simpl…
Generalized cross-resonance scheme for maximally-entangling two-qutrit gates
本文提出了一种通用交叉共振方案，用于实现最大纠缠的两量子三能级门，并通过模拟展示了多个纠缠门实例及高保真度实验结果。
Efficient High-Dimensional Quantum Circuit Synthesis: From Multi-Controlled Gates to Isometries and Quantum Channels
研究多控制门的量子电路合成，提出有效方案减少基本门数量，改进了现有复杂度界限，给出等距变换和量子通道的电路构造，首次提出特定条件下单控制门合成方案并建立理论下限。
Quantifying Entangling Power of Controlled Unitary Gates
本文提出可计算量ζ量化受控幺正门的纠缠能力，推导其通用上界并关联其他量子熵量，经对比验证该量可达到对应维度下纠缠能力的已知最优值。
Bidirectional controlled quantum state preparation in high-dimensional quantum system
本文提出一种基于两个广义 GHZ 态作为量子信道的高维量子系统双向受控远程量子态制备方案，无需高维 CNOT 操作，并证明在单光子空间模式编码下可仅用线性光学元件实现。
The fidelity of controlled quantum teleportation in a noisy environment
研究噪声信道对三比特资源态受控量子隐形传态的影响，推导最大平均保真度和最优平均保真度的解析表达式，发现最优平均保真度随演化参数先减后增的非单调行为。
The Optimization of Flux Trajectories for the Adiabatic Controlled-Z Gate on Split-Tunable Transmons
本文针对双可调频率量子比特系统，提出了一种优化参数化磁通轨迹族的通用方法，用于确定绝热调节量子比特频率的优选轨迹，并在磁通可调transmon模型上验证了五个测试轨迹族的有效性。
Recently, Hassanpour and Houshmand have proposed a protocol of controlled deterministic secure quantum communication (Quant. Info. Process, DOI 10.1007/s11128-014-0866-z (2014)). The authors compared the efficiency of their protocol with that of two other existing protocols and claimed that their protocol is efficient. Here, we have shown that the efficiency of Hassanpour Houshmand (HH) protocol is not high, and there exist several approaches through which more efficient protocols for the same task can be designed. To establish this point, we have proposed an efficient protocol of controlled d…
Quantum circuit model is the most popular paradigm for implementing complex quantum computation. Based on Cartan decomposition, we show that $2(N-1)$ generalized controlled-$X$ (GCX) gates, $6$ single-qubit rotations about the $y$- and $z$-axes, and $N+5$ single-partite $y$- and $z$-rotation-types which are defined in this paper are sufficient to simulate a controlled-unitary gate $\mathcal{U}_{cu(2\otimes N)}$ with $A$ controlling on $\mathbb{C}^2\otimes \mathbb{C}^N$. In the scenario of the unitary gate $\mathcal{U}_{cd(M\otimes N)}$ with $M\geq3$ that is locally equivalent to a diagonal uni…
In this paper, we propose a scheme to realize three-qubit controlled phase gate and multiqubit controlled-NOT gate of one qubit simultaneously controlling n target qubit with four level quantum system in a cavity. Adjustment of level spacing during the gates implementation is not required. Implementation time for multiqubit controlled NOT gate is independent of number of qubit. Three-qubit phase gate is generalized to n-qubit phase gate with multiple control qubit and the number of steps (complexity) reduces linearly as compare to conventional gate decomposition method. Our scheme can be appli…
Adiabatic cyclic modulation of a one-dimensional periodic potential will result in quantized charge transport, which is termed the Thouless pump. In contrast to the original Thouless pump restricted by the topology of the energy band, here we experimentally observe a generalized Thouless pump that can be extensively and continuously controlled. The extraordinary features of the new pump originate from interband coherence in nonequilibrium initial states, and this fact indicates that a quantum superposition of different eigenstates individually undergoing quantum adiabatic following can also be…
Efficient and deterministic high-dimensional controlled-swap gates on hybrid linear optical systems with high fidelity
本文提出利用混合线性光系统高效实现高维受控交换门，通过优化光学元件减少数量并提高保真度。
We propose a method to dynamically generate and control the flow of spin-entangled electrons, each belonging to a spin-singlet, by means of adiabatic quantum pumping. The pumping cycle functions by periodic time variation of localized two-body interactions. We develop a generalized approach to adiabatic quantum pumping as traditional methods based on scattering matrix in one dimension cannot be applied here. We specifically compute the flow of spin-entangled electrons within a Hubbard-like model of quantum dots, and discuss possible implementations and identify parameters that can be used to c…
Robustness Analysis for Quantum Systems Controlled by Continuous-Time Pulses
本文将微分灵敏度技术推广至连续时间脉冲控制的封闭量子系统，证明灵敏度消失与完美保真度一致，并基于哈密顿量和控制输入上限推导出灵敏度上界。
Defining a computational basis of pseudo-number states, we interpret a coherent state of large amplitude, $|α|\gg\frac{d}{2π}$, as a qudit --- a $d$-level quantum system --- in a state that is an even superposition of $d$ pseudo-number states. A pair of such coherent-state qudits can be prepared in maximally entangled state by generalized Controlled-$Z$ operation that is based on cross-Kerr nonlinearity, which can be weak for large $d$. Hence, a coherent-state optical qudit cluster state can be prepared by repetitive application of the generalized Controlled-$Z$ operation to a set of coherent …
Discrete quantum feedback control consists of a managed dynamics according to the information acquired by a previous measurement. Energy fluctuations along such dynamics satisfy generalized fluctuation relations, which are useful tools to study the thermodynamics of systems far away from equilibrium. Due to the practical challenge to assess energy fluctuations in the quantum scenario, the experimental verification of detailed fluctuation relations in the presence of feedback control remains elusive. We present a feasible method to experimentally verify detailed fluctuation relations for discre…
We calculate the Wigner (quasi)probability distribution function of the quantum optical elliptical vortex (QEV), generated by coupling squeezed vacuum states of two modes. The coupling between the two modes is performed by using beam splitter (BS) or a dual channel directional coupler (DCDC). The quantum interference due to the coupling between the two modes promises the generation of controlled entanglement for quantum computation and quantum tomography. We compute the entanglement of such QEV formed by non-classical radiation field, using Wigner function. We report a critical squeezing param…
In this paper, we demonstrate n-party controlled unitary gate implementations locally on arbitrary remote state through linear entangled channel where control parties share entanglement with the adjacent control parties and only one of them shares entanglement with the target party. In such a network, we describe the protocol of simultaneous implementation of controlled-Hermitian gate starting from three party scenario. We also explicate the implementation of three party controlled-Unitary gate, a generalized form of Toffoli gate and subsequently generalize the protocol for n-party using minim…
We construct multipartite graph states whose dimension is the power of a prime number. This is realized by the finite field, as well as the generalized controlled-NOT quantum circuit acting on two qudits. We propose the standard form of graph states up to local unitary transformations and particle permutations. The form greatly simplifies the classification of graph states as we illustrate up to five qudits. We also show that some graph states are multipartite maximally entangled states in the sense that any bipartite of the system produces a bipartite maximally entangled state. We further pro…
We present a numerically-optimized multipulse framework for the quantum control of a single-electron charge qubit. Our framework defines a set of pulse sequences, necessary for the manipulation of the ideal qubit basis, that avoids errors associated with excitations outside the computational subspace. A novel control scheme manipulates the qubit adiabatically, while also retaining high speed and ability to perform a general single-qubit rotation. This basis generates spatially localized logical qubit states, making readout straightforward. We consider experimentally realistic semiconductor qub…
We derive a general Hamiltonian that governs the interaction between an $N$-ion chain and an externally controlled laser field, where the ion motion is quantized and the laser field is considered beyond the plane-wave approximation. This general form not only explicitly includes terms that are used to drive ion-ion entanglement, but also a series of unwanted terms that can lead to quantum gate infidelity. We demonstrate the power of our expressivity of the general Hamiltonian by singling out the effect of axial mode heating and confirm this experimentally. We discuss pathways forward in furthe…
This paper is concerned with the discrete spectra of Schroedinger operators H = -Delta + V, where V(r) is an attractive potential in N spatial dimensions. Two principal results are reported for the bottom of the spectrum of H in each angular-momentum subspace H_{ell}: (i) an optimized lower bound when the potential is a sum of terms V(r) = V^{(1)}(r) + V^{(2)}(r), and the bottoms of the spectra of -Delta + V^{(1)}(r) and -Delta + V^{(2)}(r) in H_{ell} are known, and (ii) a generalized comparison theorem which predicts spectral ordering when the graphs of the comparison potentials V^{(1)}(r) an…
We show that the effect of measurement back-action results in the generation of multiple many-body spatial modes of ultracold atoms trapped in an optical lattice, when scattered light is detected. The multipartite mode entanglement properties and their nontrivial spatial overlap can be varied by tuning the optical geometry in a single setup. This can be used to engineer quantum states and dynamics of matter fields. We provide examples of multimode generalizations of parametric down-conversion, Dicke, and other states, investigate the entanglement properties of such states, and show how they ca…
扫码添加微信好友，提出您的宝贵建议 👇
💡 备注请填写：网站反馈
发表机构由 AI 从论文文本抽取，如发现错误，欢迎反馈修正建议。