Controlling the spontaneous emission of trapped ions (2501.08627v2)

Abstract: We propose an experimental setup for manipulating the spontaneous emission of trapped ions, based on a spatial light modulator. Anticipated novelties include the potential to entangle more than two ions through a single photon detection event and control the visibility for spatially distinguishable emitters. The setup can be adapted to most of the existing ion traps commonly used in quantum technology.

• The paper presents an innovative SLM-integrated framework that controls the spontaneous emission of trapped ions.
• The method uses Fourier phase control on the emitted photon wavefront to enable remote ion entanglement via the Cabrillo scheme.
• Comprehensive simulations demonstrate high-fidelity entangled states and scalable ion-trap configurations for quantum computing applications.

An Analysis of "Controlling the Spontaneous Emission of Trapped Ions"

The paper "Controlling the Spontaneous Emission of Trapped Ions" presents an in-depth examination of a proposed experimental setup that aims to manipulate the spontaneous emission (SE) of trapped ions through the application of a spatial light modulator (SLM). This research introduces novel methodologies for advancing the entanglement of multiple ions via single-photon detection and controlling emission visibility for spatially distinct emitters. The SLM-integrated setup can be adapted to existing ion trap technologies commonly employed in the field of quantum technologies.

Overview

The primary focus of this paper is the innovative use of an SLM to manipulate and control SE, a critical process involved in Doppler cooling and quantum-state detection in trapped ions. This innovation holds potential for enhancing quantum computing operations, particularly in entanglement creation, which is typically constrained by the proximities required for motional coupling in standard methods. The incorporation of an SLM not only allows for overcoming the limitations posed by standard geometries but also introduces adaptable phase control to manage superposition states in a more flexible manner.

Methodology

The experimental framework integrates a confocal lens system whereby ions are trapped in the focal plane. The emitted photon field from these ions undergoes modulation via the SLM, with the Fourier transformation principles employed to control the wavefront returned onto the emitting ions. This setup is rigorously modeled, accounting for practical conditions such as reflectivity, optical transmission, and the operational phase of the SLM, which ensure that the collective emission can be controlled without requiring physical realignment of the ion trap configuration.

Applications

The paper explores two primary applications:

1. Remote Entanglement: A notable application is in programmable entanglement generation using the Cabrillo scheme, an approach where entangled states among multiple ions are achieved via photon superposition at a detector point. By partitioning the SLM into sectors, each controlling the images of distinct ions for coherent overlap, the paper demonstrates a new mechanism for scalable ion entanglement well-suited for quantum computing architectures.
2. Collective Spontaneous Emission Control: By adjusting the SLM phase to satisfy a destructive interference condition, the results show that SE can be suppressed even when ions remain distinguishable in space—an achievement that diverges from traditional methods requiring indistinguishable emitters for interference.

Strong Numerical Results and Claims

The paper details the high fidelity of entangled states with negligible infidelity when weak excitation probabilities are used, backed by comprehensive simulations that validate theoretical predictions. Moreover, comparative metrics such as $P_{succ}$ and fidelity from Cabrillo protocol experiments are articulated, demonstrating substantial improvements in entanglement protocols using SLM-based systems.

Implications and Future Directions

From a theoretical perspective, this research broadens the horizon for SE manipulation and entanglement strategies in quantum optics, breaking traditional limits of ion trap configurations. Practically, the implementation of this novel setup could significantly advance current quantum processing units by reducing the complexity and operational overhead from physical ion movements (or "shuttling") to photon-mediated interactions.

Future work could further refine systems for specific quantum information applications and possibly extend these methods to other quantum systems beyond ion traps—such as cold atoms or quantum dots, which are known for their light-scattering properties. The prospect of integrating these setups into quantum networks holds promise for elevating the efficiency and scalability of quantum computers. As these techniques mature, they stand to reshape certain paradigms within quantum computing and quantum network design.