A team of physics and chemists at the University of Chicago and Northwestern University have just done something extraordinary with qubits. They managed, using chemically synthesized organometallic chromium molecules, to generate a spin state they could manipulate with microwaves and light to encode quantum information into their magnetic states. They published their findings in the research paper Optically addressable molecular spins for quantum information processing.
But what is a qubit?
A qubit is basically a unit of quantum information that possesses the strangeness of quantum mechanics. It does this by having a two-state quantum-mechanical system (superposition) rather than the one-state (binary) classical system of a bit.
This approach of creating boutique-like qubits could be a boon for quantum information systems, as having greater control over the qubits could lead to more powerful machines in the future.
One of the advantages of bringing such a diverse team together with its multidisciplinary skills is the chance to channel those researchers’ abilities in molecular design with quantum-scale systems, improving the efficacy of quantum information science (QIS).
“Some of the challenges facing quantum technologies might be able to be overcome with this very different bottom-up approach. Using molecular systems in light-emitting diodes was a transformative shift; perhaps something similar could happen with molecular qubits.”
— Sam Bayliss, a postdoctoral scholar in the Awschalom Group at the University of Chicago’s Pritzker School of Molecular Engineering and co-first author on the paper
Using controlled laser pulses to stimulate the molecules, the team could measure the total light emitted. This allowed them to interpret the spin state of the molecule during superposition, which is crucial for the molecules (qubits) to be used to send information.
Other ways the power of these molecular qubits could be harnessed is through synthetic chemistry by changing the number of atoms on the molecules, changing their magnetic as well as optical properties.
“Our results open up a new area of synthetic chemistry. We demonstrated that synthetic control of symmetry and bonding creates qubits that can be addressed in the same way as defects in semiconductors. Our bottom-up approach enables both functionalizations of individual units as ‘designer qubits’ for target applications and the creation of arrays of readily controllable quantum states, offering the possibility of scalable quantum systems,” said Danna Freedman, professor of chemistry at Northwestern University. Freedman, who was a co-author on the paper, also added: “One potential application for these molecules could be quantum sensors that are designed to target specific molecules. Such sensors could find specific cells within the body, detect when food spoils, or even spot dangerous chemicals. This bottom-up approach could also help integrate quantum technologies with existing classical technologies.”
It’s an exciting time for QIS and quantum computing (QC), and with the help of the UChicago and NU interdisciplinary team, maybe spin-bearing qubits could actually be a gamechanger in the industry.