Yilun Xu; Gang Huang; Jan Balewski; Ravi Naik; Alexis Morvan; Bradley Mitchell; Kasra Nowrouzi; David I. Santiago; Irfan Siddiqi, Author at IEEE Transactions on Quantum Engineering

QubiC: An Open-Source FPGA-Based Control and Measurement System for Superconducting Quantum Information Processors

September 29, 2021Yilun Xu; Gang Huang; Jan Balewski; Ravi Naik; Alexis Morvan; Bradley Mitchell; Kasra Nowrouzi; David I. Santiago; Irfan SiddiqiOpen Access, Quantum Computer Architecture, Quantum InformationField programmable gate arrays, Hardware, Prototypes, Quantum computing, Qubit

As quantum information processors grow in quantum bit (qubit) count and functionality, the control and measurement system becomes a limiting factor to large-scale extensibility. To tackle this challenge and keep pace with rapidly evolving classical control requirements, full control stack access is essential to system-level optimization. We design a modular field-programmable gate array (FPGA)-based system […]

Log-Domain Decoding of Quantum LDPC Codes Over Binary Finite Fields

September 21, 2021Ching-Yi Lai; Kao-Yueh KuoOpen Access, Quantum InformationBelief propagation, Correlation, Decoding, Parity check codes

A quantum stabilizer code over GF(q) corresponds to a classical additive code over GF(q2) that is self-orthogonal with respect to a symplectic inner product. We study the decoding of quantum low-density parity-check (LDPC) codes over binary finite fields GF(q = 2l) by the sum-product algorithm, also known as belief propagation (BP). Conventionally, a message in a nonbinary BP for quantum codes […]

Protocols for Packet Quantum Network Intercommunication

September 14, 2021Nengkun Yu; Ching-Yi Lai; Li ZhouOpen Access, Quantum InformationProtocols, Quantum entanglement, Quantum mechanics, Quantum networks, Qubit, Reliability, Teleportation

A quantum network, which involves multiple parties pinging each other with quantum messages, could revolutionize communication, computing, and basic sciences. The future internet will be a global system of various packet switching quantum and classical networks, and we call it quantum internet . To build a quantum Internet, unified protocols that support the distribution of […]

On the Experimental Feasibility of Quantum State Reconstruction via Machine Learning

August 24, 2021Sanjaya Lohani; Thomas A. Searles; Brian T. Kirby; Ryan T. GlasserOpen Access, Quantum InformationMachine learning, Matrix decomposition, Maximum likelihood estimation, Noise measurement, Quantum state, Qubit, Training

We determine the resource scaling of machine learning-based quantum state reconstruction methods, in terms of inference and training, for systems of up to four qubits when constrained to pure states. Further, we examine system performance in the low-count regime, likely to be encountered in the tomography of high-dimensional systems. Finally, we implement our quantum state […]

Experimental Demonstrations of Native Implementation of Boolean Logic Hamiltonian in a Superconducting Quantum Annealer

August 24, 2021Daisuke Saida; Yuki Yamanashi; Mutsuo Hidaka; Fuminori Hirayama; Kentaro Imafuku; Shuichi Nagasawa; Shiro KawabataOpen Access, Quantum Computer Architecture, Quantum InformationAnnealing, Electronics packaging, Licenses, Logic gates, Qubit, Schedules, Superconducting integrated circuits

Experimental demonstrations of quantum annealing with “native” implementation of Boolean logic Hamiltonians are reported. As a superconducting integrated circuit, a problem Hamiltonian whose set of ground states is consistent with a given truth table is implemented for quantum annealing with no redundant qubits. As examples of the truth table, nand and nor are successfully fabricated […]

Quantum Generative Models for Small Molecule Drug Discovery

August 23, 2021Junde Li; Rasit O. Topaloglu; Swaroop GhoshOpen Access, Quantum InformationChemicals, Drugs, Generative adversarial networks, Logic gates, Quantum computing, Qubit, Training

Existing drug discovery pipelines take 5–10 years and cost billions of dollars. Computational approaches aim to sample from regions of the whole molecular and solid-state compounds called chemical space, which could be on the order of 1060. Deep generative models can model the underlying probability distribution of both the physical structures and property of drugs and […]

Efficient Discrete Feature Encoding for Variational Quantum Classifier

August 10, 2021Hiroshi Yano; Yudai Suzuki; Kohei M. Itoh; Rudy Raymond; Naoki YamamotoOpen Access, Quantum InformationEncoding, Machine learning, Quantum computing, Quantum mechanics, Quantum state, Qubit, Task analysis

Recent days have witnessed significant interests in applying quantum-enhanced techniques for solving a variety of machine learning tasks. Variational methods that use quantum resources of imperfect quantum devices with the help of classical computing techniques are popular for supervised learning. Variational quantum classification (VQC) is one of such methods with possible quantum advantage in using […]

Efficient Boolean Methods for Preparing Uniform Quantum States

August 4, 2021Fereshte Mozafari; Heinz Riener; Mathias Soeken; Giovanni De MicheliOpen Access, Quantum Information, Quantum SoftwareApproximation algorithms, Boolean functions, Logic gates, Quantum circuit, Quantum state, Qubit, Runtime

As each quantum algorithm requires a specific initial quantum state, quantum state preparation is an important task in quantum computing. The preparation of quantum states is performed by a quantum circuit consisting of controlled-NOT (CNOT) and single-qubit gates. Known algorithms to prepare arbitrary n -qubit quantum states create quantum circuits in O(2n) runtime and use O(2n) CNOTs, which are more expensive […]

Efficient Optimization of Cutoffs in Quantum Repeater Chains

July 26, 2021Boxi Li; Tim Coopmans; David ElkoussOpen Access, Quantum InformationAdaptation models, Optimization, Protocols, Quantum communication, Quantum entanglement, Quantum state, Repeaters

Quantum communication enables the implementation of tasks that are unachievable with classical resources. However, losses on the communication channel preclude the direct long-distance transmission of quantum information in many relevant scenarios. In principle, quantum repeaters allow one to overcome losses. However, realistic hardware parameters make long-distance quantum communication a challenge in practice. For instance, in […]

Key Device and Materials Specifications for a Repeater Enabled Quantum Internet

July 21, 2021Manish Kumar Singh; Liang Jiang; David D. Awschalom; Supratik GuhaOpen Access, Quantum InformationDetectors, Logic gates, Photonics, Quantum entanglement, Qubit, Repeaters, Single-photon avalanche diodes

Entangled photons can be used to create a truly secure communication link between two parties. However, the distance over which this can be achieved is limited by the transmission losses associated with optical fibers. One potential solution is using quantum repeaters (QRs) where initial entanglement is created over short distances and then extended via entanglement […]