Estimation of the CHSH Parameter Using HOM Interference

The Clauser–Horne–Shimony–Holt (CHSH) experiment is an essential test of nonlocality in quantum mechanics and can be used to validate the principle of entanglement. In addition to verifying entanglement, the measurable CHSH parameter can also be used to gauge the quality of the entanglement present in a system. The measurement of Hong–Ou–Mandel (HOM) interference is another […]

Long-Term Secure Distributed Storage Using Quantum Key Distribution Network With Third-Party Verification

The quantum key distribution (QKD) network with Vernam’s one-time pad encryption and secret sharing are powerful security tools to realize an information theoretically secure (ITS) distributed storage system. In the work of Fujiwara et al., a single-password-authenticated secret sharing (SPSS) scheme based on the QKD network and Shamirs secret sharing was experimentally demonstrated; it confirmed ITS […]

Efficient Quantum Network Communication Using Optimized Entanglement Swapping Trees

Quantum network communication is challenging, as the no-cloning theorem in the quantum regime makes many classical techniques inapplicable; in particular, the direct transmission of qubit states over long distances is infeasible due to unrecoverable errors. For the long-distance communication of unknown quantum states, the only viable communication approach (assuming local operations and classical communications) is […]

A Connection-Oriented Entanglement Distribution Design in Quantum Networks

Quantum networks create a completely new way for communication, and the most important function of a quantum network is to generate long-distance quantum entanglement to serve a number of quantum applications. As the scale of the network expands, in order to establish end-to-end entanglement between two remote nodes, entangled pairs need to be generated and […]

Decentralization Using Quantum Blockchain: A Theoretical Analysis

Blockchain technology has been prominent recently due to its applications in cryptocurrency. Numerous decentralized blockchain applications have been possible due to blockchains’ nature of distributed, secured, and peer-to-peer storage. One of its technical pillars is using public-key cryptography and hash functions, which promise a secure, pseudoanonymous, and distributed storage with nonrepudiation. This security is believed […]

High-Stability Cryogenic System for Quantum Computing With Compact Packaged Ion Traps

Cryogenic environments benefit ion trapping experiments by offering lower motional heating rates, collision energies, and an ultrahigh vacuum (UHV) environment for maintaining long ion chains for extended periods of time. Mechanical vibrations caused by compressors in closed-cycle cryostats can introduce relative motion between the ion and the wavefronts of lasers used to manipulate the ions. […]

Quantum Control of Optically Active Artificial Atoms With Surface Acoustic Waves

Surface acoustic waves (SAWs) are a versatile tool for realizing coherent quantum interfaces between various solid-state qubits spanning microwave to optical frequencies. Through strain, electric, or magnetic fields associated with acoustic waves, qubit states can be controlled and measured with exquisite precision for applications in quantum information processing, memory, transduction, and sensing. In this review, […]

Model-Predictive Quantum Control via Hamiltonian Learning

This article proposes an end-to-end framework for the learning-enabled control of closed quantum systems. The proposed learning technique is the first of its kind to utilize a hierarchical design, which layers probing control, quantum state tomography, quantum process tomography, and Hamiltonian learning to identify both the internal and control Hamiltonians. Within this context, a novel […]

Qubit-Compatible Substrates With Superconducting Through-Silicon Vias

We fabricate and characterize superconducting through-silicon vias and electrodes suitable for superconducting quantum processors. We measure internal quality factors of a million for test resonators excited at single-photon levels, on chips with superconducting vias used to stitch ground planes on the front and back sides of the chips. This resonator performance is on par with […]

Noise Reduction Methods for Charge Stability Diagrams of Double Quantum Dots

Operating semiconductor quantum dots as quantum bits requires isolating single electrons by adjusting gate voltages. The transitions of electrons to and from the dots appear as a honeycomb-like pattern in recorded charge stability diagrams (CSDs). Thus, detecting the pattern is essential to tune a double dot, but manual tuning is seriously time-consuming. However, automation of […]