Molecular One- and Two-Qubit Systems with Very Long Coherence Times

General-purpose quantum computation and quantum simulation require multi-qubit architectures with precisely defined, robust interqubit interactions, coupled with local addressability. This is an unsolved challenge, primarily due to scalability issues. These issues often derive from poor control over interqubit interactions. Molecular systems are promising materials for the realization of large-scale quantum architectures, due to their high degree of positionability and the possibility to precisely tailor interqubit interactions. The simplest quantum architecture is the two-qubit system, with which quantum gate operations can be implemented. To be viable, a two-qubit system must possess long coherence times, the interqubit interaction must be well defined and the two qubits must also be addressable individually within the same quantum manipulation sequence. Here results are presented on the investigation of the spin dynamics of chlorinated triphenylmethyl organic radicals, in particular the perchlorotriphenylmethyl (PTM) radical, a mono-functionalized PTM, and a biradical PTM dimer. Extraordinarily long ensemble coherence times up to 148 & mu;s are found at all temperatures below 100 K. Two-qubit and, importantly, individual qubit addressability in the biradical system are demonstrated. These results underline the potential of molecular materials for the development of quantum architectures.

Automated summary

General-purpose quantum computation and quantum simulation require precise and robust interqubit interactions in multi-qubit architectures, along with local addressability. Molecular systems, such as chlorinated triphenylmethyl organic radicals, show promise for large-scale quantum architectures due to their high degree of positionability and tailorability of interqubit interactions. This study demonstrates extraordinarily long coherence times up to 148 μs in the investigated molecular materials at temperatures below 100 K, and also showcases two-qubit and individual qubit addressability in the biradical system. These findings highlight the potential of molecular materials for the development of quantum architectures.