Quantum computing has revolutionized the way we think about information and information processing. By building on the laws of quantum physics and phenomena such as superposition and entanglement, these devices promise to surpass the capabilities of our best classical computers. Yet, despite impressive recent developments, today's quantum processors still only use a small fraction of their true potential. Quantum computing hardware is almost exclusively built following the decades-old classical paradigm of binary information processing. The underlying physical systems that carry the quantum information, however, are almost always inherently multilevel systems. Similarly, many of the problems targeted by quantum computers also do not neatly fit into a binary paradigm. Hence, there is a twofold loss of computational efficiency: first in the use of only a fraction of the available information capacity, and second in inefficient rewriting of computational tasks into a language that is less suitable than the original formulation. This artificial restriction of quantum computers to just two levels per particle thus greatly limits the computational power of current and future quantum devices.
The goal of this project is to develop, implement, and demonstrate a quantum processor based on multi-level qudits encoded in trapped Ca40 ions. Using up to 8 levels per ion results in a vastly increased computational capacity compared to operating the same hardware with just two levels. In the first stage, this project will demonstrate universal control of multi-qudit registers for quantum computation with competitive performance. In the second stage, this new device will be used to demonstrate the utility of qudit-based quantum computing and simulation by showing how the qudit approach outperforms qubits in several key applications. Examples include qudit-enhanced tasks, such as optimal measurements, gate decompositions, or noise suppression, as well as native qudit tasks, such as quantum simulations of condensed matter and high-energy physics models with naturally exhibit a multi-level structure.
