Challenges and Opportunities of Near-Term Quantum Computing Systems

Abstract

The concept of quantum computing has inspired a whole new generation of scientists, including physicists, engineers, and computer scientists, to fundamentally change the landscape of information technology. With experimental demonstrations stretching back more than two decades, the quantum computing community has achieved a major milestone over the past few years: the ability to build systems that are stretching the limits of what can be classically simulated, and which enable cloudbased research for a wide range of scientists, thus increasing the pool of talent exploring early quantum systems. While such noisy near-term quantum computing systems fall far short of the requirements for fault-tolerant systems, they provide unique testbeds for exploring the opportunities for quantum applications.Here we highlight the facets associated with these systems, including quantum software, cloud access, benchmarking quantum systems, error correction and mitigation in such systems, and understanding the complexity of quantum circuits and how early quantum applications can run on near term quantum computers.

Leakage detection for a transmon-based surface code

“…Recent advances in qubit numbers [1][2][3][4] , as well as operational [5][6][7][8][9][10][11][12][13] , and measurement [14][15][16] fidelities have enabled leading quantum computing platforms, such as superconducting and trapped-ion processors, to target demonstrations of quantum error correction (QEC) [17][18][19][20][21][22][23] and quantum advantage 2,[24][25][26] . In particular, twodimensional stabilizer codes, such as the surface code, are a promising approach 23,27 towards achieving quantum fault tolerance and, ultimately, large-scale quantum computation 28 .…”

Quantum synchronization on the IBM Q system

“…There are still major obstacles to the simulation of complex open quantum systems, namely, (i) low two-qubit gate fidelities, (ii) a missing qubit reset operation during the calculation, and (iii) the low effective connectivity of the devices, which is partly due to point (i). While the two-qubit gate fidelities of the quantum processors in the IBM Q System have been significantly improved [38], they still strongly restrict the maximum number of controlled operations that can be performed. Taking advantage of the paradigm of synchronization, we implemented a time evolution taileored to the hardware constraints by approximating the signals with single-qubit gates.…”

“…All data presented in this article has been collected on the publicly accessible NISQ processor ibmqx2 between September 30 and October 7, 2019. This quantum processor provides 5 qubits in a star-shaped geometry where CNOT operations can be performed between the central qubit 2 and all other qubits 0, 1, 3, and 4 [38]. Additional CNOT operations are provided between the qubits 0 and 1 as well as 3 and 4, which we do not use, however.…”

1.4 The Future of Computing: Bits + Neurons + Qubits

“…Along the way, the research necessary to scale the size, performance, and stability of quantum processors has led to significant improvements in the quality and uniformity of multi-qubit systems. For example, Figure 10 plots the Controlled-NOT (CNOT) two-qubit gate error distributions measured between all available connected pairs of qubits, within four successive generations of 20-qubit quantum processors [48]. Each row corresponds to a different 20-qubit device.…”