arXiv subjects

Wonjae Choi

Publications and source records attributed to Wonjae Choi.

4 recordsLinked to original sources

arXiv2025

Effectiveness of the syndrome extraction circuit with flag qubits on IBM quantum hardware

Large scale quantum circuits are required to exploit the advantages of quantum computers. Despite significant advancements in quantum hardware, scalability remains a challenge, with errors accumulating as more qubits and gates are added. To overcome this limitation, quantum error-correction codes have been introduced. Although the success of quantum error correction codes has been demonstrated on superconducting quantum processors and neutral atom-based systems, there have been no experimental reports of error suppression using flag qubits on a quantum processor. IBM's quantum hardware features a non-topological coupling map, and past developments of quantum error correction codes on this platform have primarily explored the use of flag qubits. Here, we report the successful implementation of a syndrome extraction circuit with flag qubits on IBM quantum computers. Moreover, we demonstrate its effectiveness by considering the repetition code as a test code among the quantum error-correcting codes. Even though the data qubit is not adjacent to the syndrome qubit, logical error rates diminish as the distance of the repetition code increases from three to nine. Even when two flag qubits exist between the data and syndrome qubits, the logical error rates decrease as the distance increases similarly. This confirms the successful implementation of the syndrome extraction circuit with flag qubits on the IBM quantum computer.

quant-ph↗

arXiv2024

Implementation of Magic State Injection within Heavy-Hexagon Architecture

The magic state injection process is a critical component of fault-tolerant quantum computing, and numerous studies have been conducted on this topic. Many existing studies have focused on square-lattice structures, where each qubit connects directly to four other qubits via two-qubit gates. However, hardware that does not follow a lattice structure, such as IBM's heavy-hexagon structure, is also under development. In these non-lattice structures, many quantum error correction (QEC) codes designed for lattice-based system cannot be directly applied. Adapting these codes often requires incorporating additional qubits, such as flag qubits. This alters the properties of the QEC code and introduces new variables into the magic state injection process. In this study, we implemented and compared the magic state injection process on a heavy-hexagon structure with flag qubits and a lattice structure without flag qubits. Additionally, we considered biased errors in superconducting hardware and investigated the impact of flag qubits under these conditions. Our analysis reveals that the inclusion of flag qubits introduces distinct characteristics into the magic state injection process, which are absent in systems without flag qubits. Based on these findings, we identify several critical considerations for performing magic state injection on heavy-hexagon systems incorporating flag qubits. Furthermore, we propose an optimized approach to maximize the efficacy of this process in such systems.

quant-ph↗

arXiv2022

Directional self-propelled transport of coalesced droplets on a superhydrophilic cylindrical wire

Droplets coalescing on flat surfaces tend to end up with the smaller droplet migrating into the larger one. We report a counter-intuitive droplet coalescence pattern on a superhydrophilic cylindrical wire, where the larger droplet is pulled toward the smaller one. Consequently, the center of the combined mass significantly moves toward, often beyond, the original location of the smaller droplet. This phenomenon occurs primarily because the viscous friction that a droplet experiences on a cylindrical wire is not positively correlated with the size of the droplet, unlike the droplets coalescing on flat surfaces. We conducted a dimensional analysis based on a mass-spring-damper (MSD) model. Our model predicts a variety of coalescence patterns as a function of the ratio between droplet sizes, and the prediction matches the experimental observation.

physics.flu-dyn↗

arXiv2015

High-gravity Spreading of Liquid Coatings on Wetting Flexible Substrates

This work describes a mechanical approach for manipulating the capillary length and spreading of liquid coatings on flexible substrates with high gravity. Experimental verification in the literature has focused on cases under standard gravity on earth, and to the authors' knowledge, this work is the first to explore its relevance to spreading puddles under high gravity. By using centrifugation with a high-density liquid base underneath a coated substrate, it is possible to apply acceleration normal to a substrate to decrease the capillary length and increase the rate of spreading. Due to the nature of centrifugation, this method works primarily on flexible substrates, which bend with a curvature that conforms to a contour of uniformly distributed centrifugal acceleration. With high gravity of 600 g applied, the capillary length reduces by a factor of 24.5, and the spreading shifts from "transient spreading" between the surface tension-driven and gravity-driven regimes to the gravity-driven regime. Experimental results show that high gravitational acceleration will enhance the rate of spreading such that a puddle, which would require 12 hours under standard gravity on earth to go from an 8-μl droplet to a 40-μm thick puddle, would require less than 1 minute under 600 g. Overall, this work suggests that previously derived expressions for gravity-driven spreading of puddles under earth's standard gravity extend to predicting the behavior of puddles spreading on smooth, wetting substrates exposed to more than 100 g's of acceleration.

cond-mat.soft↗