The research team of the National Institute of Standards and Technology recently announced that it has solved a difficult scientific problem, namely how to control the quantum properties of a single charged molecule or molecular ion. The key is to use similar “quantum logic” operations that are intended for future quantum computer operations. New technologies, like laser cooling and other technologies to control atoms, effectively control molecules, and have wide application potential. Atomic quantum control will revolutionize atomic physics and lead applications such as atomic clocks, but laser pointer cooling and controlling molecules are very challenging because molecules are much more complex than atoms. The new technology still uses a laser, but the molecule can only be detected slightly, and its quantum state can only be detected indirectly. This type of molecular ion control, that is, the combination of several charged atoms, can lead to a more complex quantum information processing architecture, which amplifies basic physical research signals, such as measuring the “roundness” of electronic shapes, and increases the number of chemical reactions. control.
The quantum state of molecular ions can be found by transferring information to atomic ions, which can be cooled and controlled by laser. Drawing on the idea of the NIST quantum logic clock, the researchers tried to manipulate molecular ions. NIST researchers used ion traps and lasers that are undergoing quantum logic clock experiments to capture calcium ions that are a few millionths apart in a high vacuum chamber at room temperature. Hydrogen gas leaks into the vacuum chamber until a calcium ion reacts to form calcium hydride molecular ions that are joined by a calcium ion and a hydrogen atom.
The researchers used a green laser pointer to cool atomic ions, thereby cooling the molecules to their lowest energy state. At room temperature, molecular ions are also in their lowest electronic and vibrational states, but remain in the rotating mixture. The researchers applied infrared laser pulse modulation to prevent the electronic or vibrational state of the ions from changing, to drive the unique conversion of the molecule between two of the more than 100 possible rotation states, and then used an additional laser pulse to convert the shared motion. Changes, changing the internal energy level of atomic ions. After that, atomic ions begin to scatter light, indicating that the state of molecular ions has changed and is in the desired target state. The researchers can then transfer the angle of light emitted and absorbed during the laser-induced transition to, for example, the state of rotation of the directional molecule in the desired direction.