The Laplacian learning method has proven effective in classical graph-based semi-supervised learning, yet its quantum counterpart remains underexplored. This study systematically evaluates the Laplacian-based quantum semi-supervised learning (QSSL) approach across four benchmark datasets—Iris, Wine, Breast Cancer Wisconsin, and Heart Disease. By experimenting with varying qubit...
We provide a mathematical framework for identifying the shortest path in a maze using a Grover walk, which becomes non-unitary by introducing absorbing holes. In this study, we define the maze as a network with vertices connected by unweighted edges. Our analysis of the stationary state of the truncated Grover walk on finite graphs, where we strategically place absorbing holes...
In many quantum algorithms, including Hamiltonian simulation, efficient quantum circuit implementation of diagonal unitary matrices is an important issue. For small unitary diagonal matrices, a method based on Walsh operators is known and allows an exact implementation. Whereas, as the matrix size increases, the required resources increase linearly regarding the matrix size, so...
Quantum discord is an important measure of quantum correlations that goes beyond the paradigm of quantum entanglement. However, calculating quantum discord involves optimization over measurements, which is computationally challenging and often infeasible. This raises the intriguing question of Gaussian extremality—whether the quantum discord of a reference Gaussian state can...
In the 1970s, Wiesner introduced the concept of quantum money, where quantum states serve as currency, offering physical-level unforgeability through quantum mechanics. Yet, traditional proposals often unrealistically assume personal quantum computing access for each user. To address these issues, we propose a cloud-based semi-quantum money (CSQM) scheme. This approach only...
Trotter product formulas constitute a cornerstone quantum Hamiltonian simulation technique. However, the efficient implementation of Hamiltonian evolution of nested commutators remains an under explored area. In this work, we construct optimized product formulas of orders 3–6 approximating the exponential of a commutator of two arbitrary operators in terms of the exponentials of...
In recent years, variational quantum circuits (VQCs) have been widely explored to advance quantum circuits against classic models on various domains, such as quantum chemistry and quantum machine learning. Similar to classic machine-learning models, VQCs can be trained through various optimization approaches, such as gradient-based or gradient-free methods. However, when...
Quantum squaring circuits have been used as helpful arithmetic modules in various quantum algorithms for calculating series expansions or distances of vectors, etc. Quantum multipliers can replace quantum squaring circuits, but squaring with quantum multipliers is inefficient because it involves using quantum gates for unnecessary bitwise multiplication. In this paper, we propose...
The capacity of quantum states to send information is a fundamental and intriguing issue in quantum communication theory. This study explores a scenario where Alice intends to transmit n bits of classical information to Bob by sending m qudits, using an arbitrary bipartite pure entangled state with E qudits as the shared resource. We employ the unambiguous discrimination strategy...
We define quantization scheme for discrete-time random walks on the half-line consistent with Szegedy’s quantization of finite Markov chains. Motivated by the Karlin and McGregor description of discrete-time random walks in terms of polynomials orthogonal with respect to a measure with support in the segment $$[-1,1]$$ , we represent the unitary evolution operator of the quantum...
Quantum computing represents a revolutionary computational paradigm with the potential to address challenges beyond classical computers’ capabilities. The development of robust quantum software is indispensable to unlock the full potential of quantum computing. Like classical software, quantum software is expected to be complex and extensive, needing the establishment of a...
Quantum machine learning (QML) is one of the most promising applications of quantum computation. Despite the theoretical advantages, it is still unclear exactly what kind of problems QML techniques can be used for, given the current limitation of noisy intermediate-scale quantum devices. In this work, we apply the well-studied quantum support vector machine (QSVM), a powerful QML...
The properties of the Cournot model based on the most general entanglement operator containing quadratic expressions which is symmetric with respect to the exchange of players are considered. The degree of entanglement of games dependent on one and two squeezing parameters and their payoff values in Nash equilibrium are compared. The analysis showed that the relationship between...
We consider a two-mode bosonic state with fixed photon number $$n \in \mathbb {N}$$ , whose upper and lower modes pick up a phase $$\phi $$ and $$-\phi $$ , respectively. We compute the optimal Fock coefficients of the input state, such that the mean square error (MSE) for estimating $$\phi $$ is minimized, while the minimum MSE is always attainable by a measurement. Our setting...
Image classification is a crucial task in machine learning with widespread practical applications. The existing classical framework for image classification typically utilizes a global pooling operation at the end of the network to reduce computational complexity and mitigate overfitting. However, this operation often results in a significant loss of information, which can affect...
A binary constant weight code is a type of error-correcting code with a wide range of applications. The problem of finding a binary constant weight code has long been studied as a combinatorial optimization problem in coding theory. In this paper, we propose a quantum search algorithm for binary constant weight codes. Specifically, the search problem is formulated as a polynomial...
We present an experimental scanning-based tomography approach for near-term quantum devices. The underlying method has previously been introduced in an ensemble-based NMR setting. Here we provide a tutorial-style explanation along with suitable software tools to guide experimentalists in its adaptation to near-term pure-state quantum devices. The approach is based on a Wigner...
A few years ago Hong et al. (Quantum Inf Process 16:236, 2017) proposed a quantum identity authentication protocol using single photons and executable on currently available quantum hardware. Zawadzki later published two attacks on this protocol, and suggested a mitigation in the same work. In this comment we point out an additional vulnerability that causes the prover Alice to...
While Grover’s search algorithm is asymptotically optimal, it does not always result in a real solution. If the search fails, the algorithm must be ran again from the beginning, conditionally doubling the effective number of oracle calls. Previous research attempted to fix this issue by modifying the oracle or alternating between numerically optimized reflectors. In this paper...
Quantum networks rely on quantum teleportation, a process where an unknown quantum state is transmitted between sender and receiver via entangled states and classical communication. In our study, we utilize a continuous variable two-mode squeezed vacuum state as the primary resource for quantum teleportation, shared by Alice and Bob, while exposed to a squeezed thermal...
In this study, we investigate the effects of chromatic dispersion on single-photon temporal wave functions (TWFs) in the context of quantum communications. Departing from classical beam analysis, we focus on the temporal shape of single photons, specifically exploring generalized Gaussian modes. From this foundation, we introduce chirped and unchirped Gaussian TWFs, demonstrating...
The use and adoption of quantum computers by the wider computing community is diminished by the need to adopt new programming techniques. These techniques involve moving from a high-level language where the programmer can define and manipulate objects, to a quantum model where the programmer defines and configures the circuits at a gate level. Previous work by the authors aimed...