Novel Quantum Systems Accelerator (QSA) research shows that molecules could play a role in the future of quantum computing, particularly in specialized applications like quantum simulations and networking. The most commonly used qubits today are based on systems like neutral atoms, superconducting circuits, and trapped ions. QSA researchers have developed advanced techniques for manipulating complex molecules with optical tweezers, paving the way for more sophisticated quantum computing and simulation technologies. These advancements could ultimately lead to powerful new tools for science and technology.
Despite the challenge of working with more complex quantum objects, the field of molecular qubits is gaining momentum due to the unique properties that molecules offer. Molecules are sensitive to environmental factors like temperature, which can cause decoherence (loss of quantum information). However, their complexity can also be leveraged to create qubits that are less affected by stray magnetic fields. For instance, dipolar interactions in polar molecules allow strong qubit-qubit interactions over longer distances in long-lived rotational states, making them ideal for quantum networking or certain kinds of simulation. Additionally, the internal vibrational and rotational states allow for denser qubit encoding, which could enable more compact quantum information storage.
QSA researchers at Harvard University have made a breakthrough using ultracold molecules trapped in optical tweezers. Their research, published in a Science paper, demonstrated precise control over the quantum states of molecules, allowing for long-range dipolar spin-exchange interactions. Dipolar spin-exchange enables the magnetic properties of particles to interact and transfer quantum information between them, making it a key mechanism for quantum entanglement and scalable quantum systems. Optical tweezers, which are precise laser beams that can trap and manipulate small particles like atoms and molecules, enabled the team to arrange molecules in specific patterns. The researchers used these tweezers to arrange molecules in a specific pattern and then used the dipolar spin-exchange interactions to entangle them.
“This work is a key advancement in developing qubits for quantum computing and simulation, as molecular systems offer enhanced stability and complexity compared to atomic systems. Producing entangled molecules is a first step towards creating more flexible qubits and quantum systems,” said study co-author Yu.
Another group of QSA researchers at Harvard experimented with the use of optical tweezers to create and control an array of ultracold polyatomic molecules. These molecules, consisting of more than two atoms, were cooled to near absolute zero, exhibiting unique quantum behaviors. By arranging these molecules in a precise array with optical tweezers, the team studied their interactions in a controlled environment. Their research, published in a Nature paper, used optical tweezers to trap and manipulate individual polyatomic molecules at ultracold temperatures. These types of molecules are difficult to cool and control due to their complex internal structures. They are radically more complex than diatomic molecules used in previous work. However, the team successfully cooled and arranged them into an array.
This advancement holds significant potential for quantum computing and simulation. With more internal degrees of freedom than simpler atoms or diatomic molecules, polyatomic molecules could enable more complex quantum operations. This research opens new possibilities for molecular quantum computing, precision measurements, and exploring fundamental physics.
These groundbreaking advancements in molecular qubits highlight the growing potential of complex quantum systems for computation, simulation, and networking. With ongoing collaboration across disciplines and the co-designing and engineering of new quantum hardware, QSA team members continue to develop control systems needed to operate these devices. They are also furthering research for important applications in physics, chemistry, and materials. The center is ultimately helping shift the field from theoretical concepts to real-world tools.