Physicists initiate quantum computing using individual molecules trapped by optical tweezers, achieving entanglement.
Described as a "landmark result" by physicist Adam Kaufman, two papers unveil the potential of entangled states in molecular tweezer arrays for enhanced applications.In the late 1990s, early quantum computing demos used molecules in a solution within a nuclear magnetic resonance machine. Since then, diverse platforms, like superconducting circuits and individual ions in a vacuum, have emerged for qubit-based quantum computing, akin to classical bits.
A formidable contender in recent years involves qubits composed of neutral atoms (as opposed to ions) confined using precise laser-beam 'tweezers.'Two independent teams have made initial strides in applying the atom-focused approach to molecules. According to Lawrence Cheuk from Princeton University, molecules' added complexity provides novel avenues for encoding quantum information and unique interaction possibilities, presenting unprecedented opportunities for quantum information processing.
Very cool molecules
Both experiments utilized optical tweezers arrays, each holding a single molecule. Employing laser techniques, researchers cooled the molecules to temperatures just above absolute zero, causing them to approach a state of near-complete stillness. Manipulating their rotation, the teams utilized non-rotating molecules for the '0' state and rotating ones for the '1', with rotation quantized at one quantum of angular momentum, known as ħ.
Calcium monofluoride's strong polarity, with clustered negative charges around the fluorine atom, imparts a net positive charge to the calcium end. Researchers exploited this polarity, allowing two molecules to interact through a mutual sensing of positive and negative poles. John Doyle, a physicist from Harvard University, emphasizes the additional tuning capability provided by the dipolar interaction of molecules.
Both teams demonstrated the entanglement of molecules, creating a collective quantum system crucial for running quantum algorithms in computers.While molecular quantum computers may be slower for most applications compared to other qubit types, researchers suggest that molecules could serve as a natural setting for manipulating quantum information with 'qutrits,' featuring three states: −1, 0, and +1. This presents a potential avenue for quantum simulations of intricate materials or fundamental forces in physics.
Doyle highlights that these breakthroughs could aid in employing trapped molecules for high-precision measurements, potentially uncovering the presence of new elementary particles.
Hannah Williams, a physicist at Durham University, UK, emphasizes the remarkable progress in the field, stating, "With this achievement, they have shown that molecules will be the basis for a competitive platform capable of quantum simulation."
