arXiv subjects

Deviprasath Palani

Publications and source records attributed to Deviprasath Palani.

5 recordsLinked to original sources

arXiv2025

Robust Two-Qubit Geometric Phase Gates using Amplitude and Frequency Ramping

We demonstrate a method for generating entanglement between trapped atomic ions based on adiabatically ramped state-dependent forces. By ramping both the amplitude of the state-dependent force and the motional mode frequencies, we realize an entangling operation that is robust to motional mode occupation and drifts in the mode frequencies. We measure Bell state fidelities above 0.99 across a broad range of ramp parameters and with motional occupations up to 10 phonons. This technique enables high-fidelity entangling operations without ground-state cooling, has a reduced calibration overhead, and is well suited for both quantum logic spectroscopy applications and scalable quantum computing architectures.

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arXiv2024

Observing Time-Dependent Energy Level Renormalisation in an Ultrastrongly Coupled Open System

Understanding how strong coupling and memory effects influence the energy levels of open quantum systems is a complex and challenging problem. Here, we show these effects by probing the transition frequency of an open two-level system within the Jaynes-Cummings model, experimentally realised using Ramsey interferometry in a single trapped 25Mg+ ion. Measurements of the system, coupled to a single-mode environment, reveal a time-dependent shift in the system's energy levels of up to 15% of the bare system frequency. This shift, accurately predicted using an open system ansatz of minimal dissipation, results purely from ultra-strong system-mode interactions and the buildup of correlations. Time-averaged measurements converge to the dispersive Lamb shift predictions and match dressed-state energies, indicating that this observed shift represents a generalised Lamb shift applicable across all coupling and detuning regimes. Our findings provide direct evidence of dynamic energy level renormalisation in strongly coupled open quantum systems, although the total system-environment Hamiltonian is static; this underscores the significance of memory effects in shaping the reduced system's energy landscape. These results offer more profound insights into Hamiltonian renormalisation, essential for strong-coupling quantum thermodynamics and advancements in all quantum platforms.

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arXiv2023

Phase-Stable Traveling Waves Stroboscopically Matched for Super-Resolved Observation of Trapped-Ion Dynamics

In quantum technologies, it is essential to understand and exploit the interplay of light and matter. We introduce an approach, creating and maintaining the coherence of four oscillators: a global microwave reference field, a polarization-gradient traveling-wave pattern of light, and the spin and motional states of a single trapped ion. The features of our method are showcased by probing the 140-nm periodic light pattern and stroboscopically tracing dynamical variations in position and momentum observables with noise floors of $1.8(2)\,$nm and $8(2)~$zN$\,\mu$s, respectively. The implications of our findings contribute to enhancing quantum control and metrological applications.

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arXiv2023

High-Fidelity Transport of Trapped-Ion Qubits in a Multi-Layer Array

A variety of physical platforms are investigated for quantum control of many particles, and techniques are extended to access multiple dimensions. Here, we present our experimental study of shuttling single Mg$^+$ ions within a scalable trap-array architecture that contains up to thirteen trapping sites in a three-dimensional arrangement. We shuttle ions from a dedicated loading hub to multiple sites with a success rate of larger than $0.99999$. In a prototype application, we demonstrate the preservation of the coherence of superposition states of a hyperfine qubit during inter-site shuttling. Our findings highlight the potential of these techniques for use in future large-scale architectures.

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arXiv2020

In-situ ac Stark shift Detection in Light Storage Spectroscopy

We report on a method for measuring ac Stark shifts observed in stored light experiments while simultaneously determining the energetic splitting between the electronic ground states involved in the two-photon transition. To this end we make use of the frequency matching effect in light storage spectroscopy. We find a linear dependence on the intensity of the control field applied during the retrieval phase of the experiment. At the same time, we observe that the light shift is insensitive to the intensity of the signal field which is in contrast to continuously operated schemes using electromagnetically induced transparency (EIT) or coherent population trapping (CPT). Our results may be of importance for future light storage-based precision measurements with EIT and CPT-type devices where, in contrast to schemes using continuous exposure to optical fields, the impact of intensity fluctuations from the signal field can be suppressed.

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