Coherent transients mimicked by two-photon coherent control of a three-level system

et al. 2011

Phys. Rev. A

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We present a method that harnesses coherent control capability to two-dimensional Fourier-transform optical spectroscopy. For this, three ultrashort laser pulses are individually shaped to prepare and control the quantum interference involved in two-photon interexcited-state transitions of a V-type quantum system. In experiments performed with atomic rubidium, quantum control for the enhancement and reduction of the 5P 1/2 → 5P 3/2 transition was successfully tested in which the engineered transitions were distinguishably extracted in the presence of dominant one-photon transitions.

Section: Theoretical Modelmentioning

confidence: 99%

“…We start by considering the two-photon transition-probability amplitude written in the spectral domain given as [21] …”

Section: B Spectral Phase Shapingmentioning

confidence: 99%

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Quantum control in two-dimensional Fourier-transform spectroscopy

Lim

et al. 2011

Phys. Rev. A

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“…2 aims the direction control of the rotation axis in the x-y plane that was performed with the two Ramsey pulses (R1 and R2) probed by the ionization pulse of which the arrival time was swept in the time window of [−0.5 ps, 2.5 ps] to monitor the change in the |1 > state probability. The two Ramsey pulses were divided from a single laser pulse by a programmed acousto-optic pulse-shaper3536 (AOPS) to have the programmed phase difference Δ φ and the fixed pulse area and delay of β = π/2 and τ = 1.5 ps, respectively. Figure 2a shows the transient evolution of the |1 > state probability (circles for the experiments and lines for the theoretical calculations) according to the phase difference.…”

mentioning

confidence: 99%

Ultrafast Ramsey interferometry to implement cold atomic qubit gates

Lim

et al. 2014

Sci Rep

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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.

“…1, which comprised an ultrafast laser amplifier system equipped with pulse-shaping capability, a magneto-optical trap for cold Rb atoms, and a synchronized fluorescence detection system. The laser system and its pulse-shaping procedure were described in the earlier publications [22][23][24]. Briefly, femtosecond near-infrared laser pulses of programed spectral amplitude and phase were produced by an acousto-optic dispersive spectral filter [25] as in Fig.…”

mentioning

confidence: 99%

Coherent control of multiphoton-ionization passage of excited-state rubidium atoms

Cho

et al. 2012

Phys. Rev. A

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We have investigated multiphoton-ionization passages of rubidium atoms initiated from the excited 5P 3/2 energy state. For this we used coherent control schemes based on femtosecond laser pulse shaping applied to cold atoms spatially isolated in a magneto-optical trap. With programed laser pulses of spectral π -phase step, of which location was varied within the laser spectrum, the sequential two-photon-ionization passage along the 5P 3/2 -5D continuum was probed in terms of trap-loss spectroscopy. The coherent control two-photon-ionization method unveiled not only the resonantly enhanced two-photon ionization but also the asymmetric nature of the ionization profile structure given as a function of the spectral phase step location. Experimental results show good agreement with the second-order perturbation calculation of the constituent possible ionization passages.