Terahertz Impulse Spectroscopy Lab

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Half Cycle Pulses

Population Redistribution of Rydberg Atoms

Ultrafast Magnetization Dynamics

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Andrew Speck

Pankaj Mandal

Rowland Institute

Overview

Our lab studies the response of systems to ultrafast electromagnetic pulses. These pulses have a temporal width of approximately 1 ps and a peak field of over 1 kV/cm when focussed. Due to their extremely short pulse width, most systems respond to these pulses in an impulsive manner implying that we are observing their temporal response to a delta function excitation as opposed to their frequency domain response. This provides complementary information to typical continuous-wave spectroscopy.

Of the many systems that have interesting impulse response functions, we have studied two in particular. First, the response of highly excited Rydberg atoms to a train of unipolar pulses that provide impulsive kicks to the valence electron. Here these kicks change the momentum of the electron and induce rapid population redistribution. Second, the same pulse also provides a unipolar magnetic field that we use to probe the response of magnetic thin films to ultrafast magnetic pulses. Our lab has developed techniques to apply and then observe the response to these pulses in free space.

Atom Trap with Rydberg Atom Detection



Unipolar Electromagnetic Pulse Emitter