Influence of Indefinite Causal Order on Otto Heat Engine

Quantum effect plays important roles in quantum thermodynamics, and recently the application of indefinite causal order to quantum thermodynamics has attracted much attentions. Based on two trapped ions, we propose a scheme to add an indefinite causal order to the isochoric cooling stroke of Otto engine through reservoir engineering. Then, we observe that the quasi-static efficiency of this heat engine is far beyond the efficiency of a normal Otto heat engine and may reach 1. When the power is its maximum, the efficiency is also much higher than that of a normal Otto heat engine. This enhancement may origin from the non-equilibrium of reservoir and the measurement on control qubit.

Fisher and Skew Information Correlations of Two Coupled Trapped Ions: Intrinsic Decoherence and Lamb-Dicke Nonlinearity

It is well known that many quantum information processing methods in artificial atoms depend largely on their engineering properties and their ability to generate quantum correlations. In this paper, we investigate the non-classical correlation dynamics of two trapped ions by using local quantum Fisher information, local quantum uncertainty, as well as logarithmic negativity. The system engineering is designed such that the two-trapped-ions work as two diploe-coupled qubits in a Lamb-Dicke regime. The center-of-mass vibrational modes are initially in coherent/even coherent states. It is found that the two-trapped-ions correlations can be controlled by the Lamb-Dicke nonlinearity, the nonclassicality effect of the initial center-of-mass vibrational mode, as well as the trapped-ion coupling and the intrinsic decoherence. The sudden changes in the non-classical correlations and their stability are shown against Lamb-Dicke nonlinearity, the nonclassicality, the trapped-ion coupling, and the intrinsic decoherence.

NONLOCALITY DYNAMICS INDUCED BY A LAMB–DICKE NONLINEARITY IN TWO DIPOLE-COUPLED TRAPPED IONS UNDER INTRINSIC DECOHERENCE

In this paper, we explore the nonlinear dynamics of two dipole-coupled-trapped ions in the Lamb–Dicke regime. The dynamics of the generated two-trapped-ions correlations under intrinsic decoherence is quantified by Bell function, the uncertainty-induced nonlocality, and the concurrence. We investigate the effects of the Lamb–Dicke nonlinearity, the intrinsic decoherence, and the two-trapped-ions coupling. It is found that the two-trapped-ions state has different nonlocal correlations. These correlations can be controlled. In the absence of decoherence, the nonlocal correlations can be enhanced by the Lamb–Dicke nonlinearity and the two-trapped-ions coupling. The stable value and the sudden death-birth phenomenon of the entanglement can be apperceived due to the increase of the Lamb–Dicke nonlinearity. The intrinsic decoherence reduces and stabilizes the nonlocal correlations. They are more pronounced with large Lamb–Dicke values. The decoherence effects are reduced by the strong Lamb–Dicke nonlinearity.

Ultrafast High-Voltage Kicker System for Ion-Clearing Gaps

Ionization scattering of electron beams with residual gas molecules causes ion trapping in electron rings, both in a collider and electron cooling system. These trapped ions may cause emittance growth, tune shift, halo formation, and coherent coupled bunch instabilities. In order to clear the ions and prevent them from accumulating turn after turn, the gaps in a temporal structure of the beam are typically used. Typically, the gap in the bunch train has a length of a few percent of the ring circumference. In those regions, the extraction electrodes with high pulsed voltages are introduced. In this paper, we present the design consideration and initial test results of the high-voltage pulsed kicker hardware that includes vacuum device and pulsed voltage driver, capable of achieving over 3 kV of deflecting voltage amplitude, rise and fall times of less than 10 ns, 100 ns flat-top duration at 1.4 MHz repetition rate.

Conformer-specific polar cycloaddition of dibromobutadiene with trapped propene ions

Diels–Alder cycloadditions are efficient routes for the synthesis of cyclic organic compounds. There has been a long-standing discussion whether these reactions proceed via stepwise or concerted mechanisms. Here, we adopt an experimental approach to explore the mechanism of the model polar cycloaddition of 2,3-dibromo-1,3-butadiene with propene ions by probing its conformational specificities in the entrance channel under single-collision conditions in the gas phase. Combining a conformationally controlled molecular beam with trapped ions, we find that both conformers of the diene, gauche and s-trans, are reactive with capture-limited reaction rates. Aided by quantum-chemical and quantum-capture calculations, this finding is rationalised by a simultaneous competition of concerted and stepwise reaction pathways, revealing an interesting mechanistic borderline case.