QUART&T
(QUantum Architectures for Theory & Technology)
The QUART&T (QUantum Architectures for Theory & Technology) project aims to develop demonstrator quantum architectures, establishing the foundation for experimental platforms where theoretical models and phenomena of interest to the INFN can be tested. In theoretical physics, one
of the most daunting computational challenges has been studying the dynamics of quantum manybody systems. These systems are often described using quantum mechanics, which introduces complexities due to the repeated interactions between particles, leading to quantum correlations
and entanglement. The study of many-body systems is crucial in various fields including atomic physics, molecular physics, nuclear physics, quantum chromodynamics, condensed matter physics, quantum chemistry and even quantum gravity. Traditional computers struggle to accurately model
the behavior of many-body systems due to the exponential growth of computational resources required as the system size increases. This limitation has hindered our understanding of many phenomena such as nuclear and subnuclear processes and, for quantum gravity, this is even more
unfortunate given the lack of direct experiments, whereas established theoretical correspondences, quantum many-body/low dimensional gravity, are opening the era of indirect experiments.
The QUART&T Project proposes to leverage the competences, skills, and infrastructure acquired in previous INFN projects to address this challenge by utilizing the unique properties of analog quantum computers. Unlike their digital counterparts, analog quantum computers operate on continuous variables and can directly simulate quantum systems, potentially offering a more efficient and accurate approach to many-body simulations. By encoding the relevant parameters into the quantum states of the analog computer, the project aims to achieve a more faithful representation of the underlying quantum dynamics.
Analog quantum computing is based on the ability to manipulate a quantum system by engineering changes in coupling parameters (interactions and/or external fields) in order to best control a quantum circuit for a specific task. The QUART&T project aims to develop a quantum architecture based on superconducting resonators and qubits (or qudits) characterized by all-toall coupling controlled by tunable couplers. Developing superconducting quantum devices is a complex process requiring a range of skills, from theoretical modeling to electromagnetic design, multi-step fabrication using optical and electron lithography, control of qubits with microwave pulses generated by FPGA-assisted board, single-shot readout of qubit states with quantum amplifiers, all cooled down in a dilution refrigerator to a few mK. The QUART&T research team succeeded in bringing these skills together through the participation of two INFN National Laboratories, nine INFN Units, and, external to INFN, two of the main micro and nano-fabrication facilities in Italy. At the end of the project, the developed architectures will be used for simple many-body simulations of physical interest, such as the (p, d), (p, 3H), or (p, 3He) scattering processes, which already present all the typical difficulties of more elaborate interactions. The versatility of the developed architectures will also be studied for applications in quantum sensing, quantum machine learning and quantum gravity.