Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2607.11973

On the Experimental Determination of Nonlocal Characteristics of Two-Qubit Gates

M. Karthick Selvan·S. Balakrishnan
View original source ↗Read source document ↗Export metadata ↓

Abstract

In this paper, we discuss the experimental determination of the nonlocal characteristics of two-qubit gates. Based on the recently derived expressions for the entangling power and gate typicality of two-qubit gates, we construct two-qubit quantum circuits to measure the entangling power and gate typicality of the two-qubit gates, which are generated by the elements of the su(4) Cartan subalgebra. These elements describe the native interactions in many quantum processors. Hence, these circuits can be used to determine the nonlocal characteristics of native gates of many quantum processors. In each circuit, the native gate is applied twice. In addition, each circuit consists of at least one CNOT gate. A set of six two-qubit circuits is constructed to measure the entangling power. The number of circuits is further reduced to three by increasing the nonlocal resources (the number of CNOT gates). To measure the gate typicality, a set of three two-qubit circuits is constructed. Measurement of gate typicality requires more nonlocal resources than the measurement of entangling power.

Explore related subjects

quant-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M. Karthick Selvan, S. Balakrishnan. 2026-07-13. On the Experimental Determination of Nonlocal Characteristics of Two-Qubit Gates. https://arxiv.org/abs/2607.11973

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Quantum Authenticated Key Expansion with Key Recycling

Data privacy and authentication are two main security requirements for remote access and cloud services. While QKD has been explored to address data privacy concerns, oftentimes its use is separate from the client authentication protocol despite implicitly providing authentication. Here, we present a quantum authentication key expansion (QAKE) protocol that (1) integrates both authentication and key expansion within a single protocol, and (2) provides key recycling property - allowing all authentication keys to be reused. We analyse the security of the protocol in a QAKE framework adapted from a classical authentication key exchange (AKE) framework, providing separate security conditions for authentication and data privacy. We experimentally implemented the protocol with appropriate post-selection. Additional results on the security of pseudorandom basis generation in QAKE and decoy state BB84 are provided.

quant-ph↗
arXiv2026

Entanglement as Difference: Reduction-induced Minimal Partial Entropy Difference

Bipartite mixed-state quantum entanglement (QE) and its measures play a crucial role in both theoretical research and practical quantum applications. Its internal structure is far more complex and less well understood compared with bipartite pure-state QE. Some existing measures involve inherently intractable global optimizations, while others are only applicable to highly limited-dimensional quantum systems. Here based on the inherent feature that bipartite QE systems nonseparable necessarily implies that local reduced density matrix differs from its \textquotedblleft native\textquotedblright density matrix, we propose a more physical and intuitive measure termed Reduction-induced Minimal Partial Entropy Difference to quantify arbitrary bipartite mixed-state QE. Partial Von Neumann Entropy is only a pure-state special case of this method. This measure offers intrinsic structural %perspective insights into bipartite QE characterization, thereby establishing itself as a valuable complementary measure. Its intuitive and clear physical picture, combined with relatively low computational complexity and wide applicability, facilitates exploring its potential quantum information applications, hence its conceptual framework and line of thought deserve to be further developed to describe and quantify multipartite QE in the future.

quant-ph↗
arXiv2026

Non-local mass superpositions and optical clock interferometry in atomic ensemble quantum networks

Quantum networks are emerging as powerful platforms for sensing, communication, and fundamental tests of physics. We propose a programmable quantum sensing network based on entangled atomic ensembles, where optical clock qubits realize mass superpositions arising via mass-energy equivalence, as in atom and atom-clock interferometry. Our approach uniquely combines scalability to large atom numbers with minimal control requirements, relying only on collective addressing of internal atomic states. This enables the creation of both non-local and local superpositions with spatial separations beyond those achievable in conventional matter-wave interferometry with single atoms. Starting from Bell-type seed states distributed via photonic channels, collective operations within atomic ensembles coherently build many-body mass superpositions sensitive to gravitational redshift. The resulting architecture implements a non-local Ramsey interferometer, where gravitationally induced phase shifts are imprinted on non-local entangled states and are read out through local measurements at the network nodes. Beyond extending the spatial reach of mass superpositions, our scheme establishes a scalable, programmable platform to probe the interface of quantum mechanics and gravity, and offers a new experimental pathway to test atom and atom-clock interferometer proposals, e.g. for probing gravitational dephasing, in a network-based quantum laboratory.

quant-ph↗