Related Experiment Video
Updated: May 9, 2026
08:22
Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
Direct measurement of the van der Waals interaction between two Rydberg atoms.
L Béguin1, A Vernier, R Chicireanu
1Laboratoire Charles Fabry, Institut d'Optique, CNRS, Univ Paris Sud, 2 avenue Augustin Fresnel, 91127 Palaiseau cedex, France.
Physical Review Letters
|July 16, 2013
Summary
Scientists directly measured the van der Waals interaction between two Rydberg atoms. This research observed partial Rydberg blockade and confirmed the C6/R6 dependence of the interaction, crucial for quantum technologies.
Area of Science:
- Atomic Physics
- Quantum Optics
- Intermolecular Forces
Background:
- Rydberg atoms, highly excited atoms with large principal quantum numbers, exhibit strong interactions.
- Understanding van der Waals (vdW) forces is fundamental in atomic and molecular physics.
- Precise control over interatomic interactions is key for developing quantum computing and sensing technologies.
Purpose of the Study:
- To directly measure the van der Waals interaction between two isolated Rydberg atoms.
- To investigate the phenomenon of partial Rydberg blockade in a controlled experimental setup.
- To quantitatively determine the vdW energy and its dependence on interatomic distance and principal quantum number.
Main Methods:
- Utilized a system of two isolated, single Rydberg atoms with precisely controlled interatomic distances (micrometer scale).
- Operated in a regime where the single-atom Rabi frequency was comparable to the interaction strength.
- Employed time-dependent population measurements and analyzed coherent oscillations using a model based on optical Bloch equations.
Main Results:
- Observed partial Rydberg blockade, characterized by coherent oscillations in two-atom state populations.
- Successfully extracted the van der Waals energy, confirming its characteristic C6/R6 dependence.
- Measured C6 coefficients showed excellent agreement with ab initio calculations and a significant increase with the principal quantum number (n).
Conclusions:
- The study provides a direct and quantitative measurement of van der Waals interactions between Rydberg atoms.
- The observed partial Rydberg blockade and confirmed C6/R6 dependence validate theoretical models.
- Results highlight the strong dependence of vdW interactions on the principal quantum number, offering insights for Rydberg-based quantum applications.
Related Concept Videos
01:24Van der Waals Interactions
Atoms and molecules interact with each other through intermolecular forces. These electrostatic forces arise from attractive or repulsive interactions between particles with permanent, partial, or temporary charges. The intermolecular forces between neutral atoms and molecules are ion–dipole, dipole–dipole, and dispersion forces, collectively known as van der Waals forces.
01:26The Van der Waals Equation
The ideal gas law is based on two simplifying assumptions: first, that there are no intermolecular attractions between gas molecules, and second, that the volume occupied by the molecules themselves is negligible compared with the volume of the container. However, these assumptions don't hold up under all conditions - specifically, at high pressures and low temperatures, as gas tends to deviate from ideal gas behavior.The van der Waals equation is an enhanced version of the ideal gas law,...
01:10Van der Waals Equation
The ideal gas law is an approximation that works well at high temperatures and low pressures. The van der Waals equation of state (named after the Dutch physicist Johannes van der Waals, 1837−1923) improves it by considering two factors.
First, the attractive forces between molecules, which are stronger at higher densities and reduce the pressure, are considered by adding to the pressure a term equal to the square of the molar density multiplied by a positive coefficient a. Second, the volume...
First, the attractive forces between molecules, which are stronger at higher densities and reduce the pressure, are considered by adding to the pressure a term equal to the square of the molar density multiplied by a positive coefficient a. Second, the volume...
04:01Real Gases: Effects of Intermolecular Forces and Molecular Volume Deriving Van der Waals Equation
Thus far, the ideal gas law, PV = nRT, has been applied to a variety of different types of problems, ranging from reaction stoichiometry and empirical and molecular formula problems to determining the density and molar mass of a gas. However, the behavior of a gas is often non-ideal, meaning that the observed relationships between its pressure, volume, and temperature are not accurately described by the gas laws.
01:16IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
A covalently bonded heteronuclear diatomic molecule can be modeled as two vibrating masses connected by a spring. The vibrational frequency of the bond can be expressed using an equation derived from Hooke's law, which describes how the force applied to stretch or compress a spring is proportional to the displacement of the spring. In this case, the atoms behave like masses, and the bond acts like a spring.
According to Hooke's law, the vibrational frequency is directly proportional to the...
According to Hooke's law, the vibrational frequency is directly proportional to the...
01:17Chemical Shift: Internal References and Solvent Effects
In an NMR sample, precise measurement of the absolute absorption frequencies of nuclei is difficult. A standard internal reference compound is added, and the frequency difference between the reference signal and sample signals is measured.
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...