Importance of attosecond research

An attosecond is one quintillionth of a second (1x10^-18 of a second), roughly equivalent to the relationship between one second and the age of the universe. Because attosecond pulses are faster than the motion of electrons within atoms and molecules, they provide a new tool to control and measure quantum states of matter.

Electrons are negatively-charged elementary particles that make everyday things like electricity possible. The interaction of light with electrons is the basis for photosynthesis and the operation of solar cells. In this experiment, scientists irradiated neon atoms with attosecond pulses to create an excited state of neon. At the same time, a precisely synchronized infrared laser pulse provided the extra energy needed to ionize the neon atom, resulting in the ejection of an electron. Because of the precise combination of laser pulses, the quantum state of the ejected electron could be controlled. Each electron was ejected in six different directions at the same time, due to the magic of quantum mechanics.

Because the electron’s wave function has an imaginary part, it is impossible to record an image.   The quantum wave function “collapses” when it is measured, so only the absolute value of the wave function can be seen. To access the imaginary part of the wave function, another coherent pathway to freeing the electron is added, creating a holographic reference. This enables both the amplitude and sign of the wave function to be imaged.