Quantum technologies promise secure communication, faster computing, and powerful sensing. But building blocks that connect seamlessly to existing networks remain elusive. A major challenge lies in bridging light, often used to transmit quantum information, with magnetism, which underpins many quantum devices.<\/p>\n
Now, researchers from the University of Chicago, UC Berkeley, Argonne National Laboratory, and Lawrence Berkeley National Laboratory say they have found a way forward.<\/p>\n
They developed molecular qubits that operate at telecommunications frequencies, linking magnetism and light. Their advance points to scalable quantum networks that could integrate directly with fiber-optic infrastructure.<\/p>\n
The new qubits rely on erbium, a rare-earth element valued for its clean optical properties and strong magnetic interactions. <\/p>\n
This combination allows the molecules to function as a bridge between two key elements of quantum technology.<\/p>\n
\u201cThese molecules can act as a nanoscale bridge between the world of magnetism and the world of optics,\u201d said Leah Weiss, postdoctoral scholar at the University of Chicago Pritzker School of Molecular Engineering and co-first author. <\/p>\n
\u201cInformation could be encoded in the magnetic state of a molecule and then accessed with light at wavelengths compatible with well-developed technologies underlying optical fiber networks and silicon photonic circuits.\u201d<\/p>\n
By uniting optics and magnetism, the team established a molecular building block that could communicate through today\u2019s optical infrastructure while supporting magnetic-based quantum operations.<\/p>\n
Toward the quantum internet<\/p>\n
Operating at telecom-band frequencies gives the qubits potential far beyond the lab. <\/p>\n
Future \u201cquantum internet\u201d systems could use them to create ultra-secure communication, link quantum computers<\/a> across distances, or deploy precise quantum sensors.<\/p>\n \u201cThese molecules could be embedded in unusual environments\u2014such as biological systems\u2014to measure magnetic fields, temperature, or pressure at the nanoscale,\u201d the researchers noted. <\/p>\n Their chemical flexibility means they could adapt to diverse environments, including silicon-based chips.<\/p>\n Grant Smith, a graduate student at UChicago PME and co-first author, said the work expands available quantum platforms. <\/p>\n \u201cThere were a lot of things pointing toward this as an exciting platform to advance the use of optical degrees of freedom in molecular spin qubits,\u201d he said. He added that broadening the set of systems available allows researchers to \u201cbegin to think about new and unconventional ways to utilize and integrate them into technologies.\u201d<\/p>\n Built for integration<\/p>\n Optical spectroscopy and microwave tests showed the molecular qubits align with frequencies already used in silicon photonics. <\/p>\n These are central to telecommunications, high-performance computing, and advanced sensing.<\/p>\n \u201cBy demonstrating the versatility of these erbium molecular qubits, we\u2019re taking another step toward scalable quantum networks that can plug directly into today\u2019s optical infrastructure,\u201d said David Awschalom, the Liew Family Professor of Molecular Engineering and Physics at UChicago and principal investigator.<\/p>\n He added that the molecules already display the properties needed for multi-qubit architectures, opening paths to applications in sensing and hybrid quantum systems.<\/p>\n The study relied heavily on collaboration with chemists at UC Berkeley. <\/p>\n Ryan Murphy, co-first author, said, \u201cSynthetic molecular chemistry provides an opportunity for optimizing the electronic and optical properties of rare earth ions in ways that can be difficult to access in conventional solid-state substrates.\u201d<\/p>\n Jeffrey Long, chemistry professor at UC Berkeley and co-principal investigator, said, \u201cOur work shows that synthetic chemistry can be used to design and control quantum materials at the molecular level. This points to a powerful route for creating tailor-made quantum<\/a> systems with applications in networking, sensing, and computation.\u201d<\/p>\n