Definition of Rabi oscillations

Photonics Dictionary

Rabi oscillations: Rabi oscillations are a fundamental phenomenon in quantum mechanics that describe the periodic and reversible exchange of energy between two quantum states when subjected to an oscillating external field, such as an electromagnetic field. They are named after the physicist Isidor Rabi, who first observed these oscillations in atomic spectroscopy experiments in the 1930s.

Rabi oscillations occur when the frequency of the external field matches the energy difference between the two quantum states, known as the resonance condition. When this condition is met, the external field induces transitions between the states by causing the system to absorb and emit quanta of energy (photons) at a characteristic Rabi frequency.

The dynamics of Rabi oscillations can be understood using the concept of quantum superposition. Initially, if the system is prepared in one of the two quantum states (e.g., ground state or excited state), it is in a pure state corresponding to that state. As the external field interacts with the system, it induces a superposition of the two states, where the probability amplitude of each state oscillates sinusoidally in time.

The frequency of the Rabi oscillations is determined by the Rabi frequency, which depends on factors such as the strength of the external field, the transition dipole moment between the states, and the energy separation between the states. The amplitude of the oscillations depends on the duration and intensity of the external field, as well as the initial state preparation.

Rabi oscillations have important implications in various areas of quantum physics and quantum technology, including quantum computing, quantum optics, atomic and molecular spectroscopy, and quantum control. They are used, for example, in techniques such as stimulated Raman adiabatic passage (STIRAP), quantum gates in quantum computing, and precision measurements in atomic and molecular physics. Understanding and controlling Rabi oscillations is essential for manipulating and harnessing quantum systems for practical applications.