Quantum computing aims for diversity, one qubit at a time

Santiago De-Giuda, Felipe Guasch, Laura Gatti +2 more

Quantum computing has emerged as a revolutionary paradigm with the potential to tackle complex computational problems more efficiently than classical systems. This paper investigates the execution of quantum algorithms on IBM's Quantum Platform, a premier cloud-based ecosystem combining classical and quantum resources. It delves into quantum circuits, emphasizing the interplay between classical data preparation, quantum gate operations, and post-processing. The configuration options available within IBM's platform and their influence on workflow execution time are analyzed. A critical aspect of this study is the cost structure of executing quantum algorithms, particularly the role of QPU usage, where factors such as the number of qubits, circuit depth, and two-qubit gate operations contribute significantly to both time and cost. By understanding these elements, we aim to offer insights into the practical challenges of utilizing quantum computing in diverse fields of the consumer industry such as cryptography, optimization, and industrial automation.

Madhusudan Singh Irish Singh, Bharat S. Rawal

Jeremy J. Ramsden

Peng Zhao, Teng Ma, Yirong Jin +1 more

With the long coherence time, fixed-frequency transmon qubits are a promising qubit modality for quantum computing. Currently, diverse qubit architectures that utilize fixed-frequency transmon qubits have been demonstrated with high-fidelity gate performance. Nevertheless, the relaxation times of transmon qubits can have large temporal fluctuations, causing instabilities in gate performance. The fluctuations are often believed to be caused by nearly on-resonance couplings with sparse two-level-system (TLS) defects. To mitigate their impact on qubit coherence and gate performance, one direct approach is to tune the qubits away from these TLSs. In this work, to combat the potential TLS-induced performance fluctuations in a tunable-bus architecture unitizing fixed-frequency transmon qubits, we explore the possibility of using an off-resonance microwave drive to effectively tune the qubit frequency through the ac Stark shift while implementing universal gate operations on the microwave-dressed qubit. We show that the qubit frequency can be tuned up to 20 MHz through the ac Stark shift while keeping minimal impacts on the qubit control. Besides passive approaches that aim to remove these TLSs through more careful treatments of device fabrications, this work may offer an active approach towards mitigating the TLS-induced performance fluctuations in fixed-frequency transmon qubit devices.

Robson Giles

Iaakov Exman

Quantum Software, its engineering and its applications are becoming more and more indispensable components of the current knowledge baggage of researchers and industrial professionals. Given the continuous accelerating developments of Quantum Computing, and the vastness of available knowledge, one needs efficient methods to dedicate the limited available personal time to the correct choice of selective information. This Special Issue on “Quantum Computing and Software Engineering” offers a small, but diverse set of papers covering theoretical, practical software system design and a pragmatic survey of Quantum Software Engineering, being a map pointing to references of relevance, aiming to answer the issue of choice of selective information.