Sangkyung Lee

Strong spin-lattice coupling in multiferroic hexagonal manganite YMnO3 probed by ultrafast optical spectroscopy

We report the observation of spin-lattice coupling in multiferroic YMnO3 by femtosecond near-infrared pump and probe spectroscopy. A coherent 31 GHz acoustic phonon was detected above the magnetic ordering temperature, and a higher frequency coherent mode was observed in the antiferromagnetic phase. This temperature-dependent measurement demonstrates that the acoustic phonon excitation is coupled to spin ordering.

Ultrafast Ramsey interferometry to implement cold atomic qubit gates

Quantum computing is based on unitary operations in a two-level quantum system, a qubit, as the fundamental building block, and the ability to perform qubit operations in an amount of time that is considerably shorter than the coherence time is an essential requirement for quantum computation. Here, we present an experimental demonstration of arbitrary single-qubit SU(2) quantum gate operations achieved at a terahertz clock speed. Implemented by coherent control methods of tailored ultrafast laser interaction with cold rubidium atomic qubits, Bloch vector manipulation about all three rotational axes was successfully demonstrated. The dynamic evolution of the qubits was successfully measured by devised femtosecond Ramsey interferometry. We anticipate this demonstration to be a starting point to process quantum algorithm in a simplified manner by a programmed sequence of femtosecond laser pulses.

Optical repumping of triplet-Pstates enhances magneto-optical trapping of ytterbium atoms

Radiative decay from the excited

Strong-field two-photon absorption in atomic cesium: an analytical control approach

^1P_1

Strong-field quantum control of 2 + 1 photon absorption of atomic sodium

state to metastable

Quantum Control of Strong-Field Ladder Climbing in Atomic Sodium

^3P_2

Coherent Control of Wavefundtions in 2-D Fourier Transform Optical Spectroscopy

and

NONLOCALITY IMPROVES DEUTSCH ALGORITHM

^3P_0

Elaboration of Linear-optical Implementations of Quantum Algorithms with Single and Double-photon Entangled States

states is expected to limit attainable trapped atomic population in a magneto-optic trap of ytterbium (Yb) atoms. In experiments we have carried out with optical repumping of

Effects of Atomic Motion on the Controllable Nonclassical Photon Statistics

^3P_{0,2}