Quantum-computing approach uses single molecules as qubits for first time
Physicists have made progress in building quantum computers using individual trapped molecules as qubits.
Underdog technologies gain ground in quantum-computing race
In the race to develop quantum computers, researchers have explored various platforms, including superconducting circuits, individual ions, and neutral atoms trapped with laser tweezers. Now, two teams have made early progress towards using individual molecules as qubits. Lawrence Cheuk, a physicist at Princeton University, explains that molecules offer new ways to encode and process quantum information. This development opens up unprecedented possibilities for the field of quantum computing.
The two recent studies involved arrays of optical tweezers, with one molecule trapped in each tweezer unit. The molecules were cooled to extremely low temperatures, close to absolute zero, which allowed their rotation to be controlled. By manipulating the rotation, the teams were able to represent the '0' and '1' states of the qubits. The researchers successfully demonstrated that the molecules became entangled, an essential requirement for quantum computers to operate.
While molecular quantum computers may be slower than other qubit types for most applications, they offer advantages in manipulating quantum information using 'qutrits' — quantum systems with three possible states. By using qutrits, researchers can conduct quantum simulations of complex materials or fundamental forces. Additionally, trapped molecules could be used for high-precision measurements to uncover new elementary particles.
Very cool molecules
Both studies focused on calcium monofluoride, a highly polar molecule. The researchers took advantage of the dipolar interaction between the molecules to induce entanglement. By 'feeling' each other's positive and negative charges, the molecules could interact and form a collective quantum system.
To achieve the desired control, the teams used arrays of optical tweezers to trap the individual molecules. Through laser techniques, the molecules were cooled to temperatures just above absolute zero, resulting in a state of near stillness. The rotation of the molecules could be halted or manipulated at the quantum level, allowing for precise control over the qubits.
Advancing the field of quantum simulation
The recent progress in using molecules as qubits showcases the rapid development in the field of quantum computing. While molecular quantum computers may not be as fast as other platforms, they offer unique capabilities for quantum simulation. Researchers believe that using molecules as qubits can lead to significant advancements in quantum simulations of complex materials and fundamental forces.
Hannah Williams, a physicist at Durham University, describes the achievement as a demonstration that molecules can serve as a competitive platform for quantum simulation. The ability to manipulate quantum information using molecules opens up new possibilities for enhancing the potential applications of quantum computers.
