arXiv subjects

S. P. Dinesh

Publications and source records attributed to S. P. Dinesh.

7 recordsLinked to original sources

arXiv2026

Gate-based emulation of boson sampling using photonic qubits

Boson sampling arising from multiphoton interference in linear-optical networks is a prominent non-universal model for quantum computation. Here, by encoding the multi-qubit state to bosonic Fock state, we present a scalable quantum-circuit framework for simulating boson sampling on a universal quantum computing platform. Beginning with balanced beam-splitter transformations on the single- and two-photon sectors, we derive equivalent quantum-circuit implementations and unify them within a common Hilbert-space representation using an ancilla-assisted encoding. This construction is then generalized to arbitrary interferometers by replacing each optical beam splitter with a repeating quantum-circuit unit that selectively acts only within the relevant local interference subspace, requiring $N+1$ qubits for a two-photon $N$-mode interferometer and a linear-overhead subspace-identification procedure. Using this framework, gate-based quantum circuit for a four-mode boson-sampling circuit is developed and experimentally implemented on a four-qubit gate-based photonic qubit system. The qubit framework for emulating boson sampling of $n-$photons in $m-$mode will be useful to solve a broad class of sampling complexity problem on a gate-based quantum computers.

quant-ph↗

arXiv2025

Experimental realization of universal quantum gates and six-qubit entangled state using photonic quantum walk

For quantum computation using photons, performing deterministic quantum gate operations is a challenge due to the probabilistic nature of the photon-photon interaction. Encoding qubits in multiple degrees-of-freedom of photons and controlling operations between them is one of the promising ways to navigate the probabilistic behavior. Using single-photon discrete-time quantum walk in combination with polarization and path degrees-of-freedom, we experimentally demonstrate the realization of a universal set of quantum gates with high fidelity at room temperature. The deterministic realization of quantum gates through photonic quantum walk are characterized via quantum state tomography. For a three-qubit system using a single photon, the first qubit is encoded using polarization information, and the other two qubits are encoded using path information, closely resembling a Galton-board setup. To generate a six-qubit Greenberger-Horne-Zeilinger state, entangled photon pairs are used to entangle the two three-qubit modules on which gate operations are performed. We also provide insights into the mapping of photonic quantum walk operations to quantum circuits and propose methods to resourcefully scale. This demonstration marks a significant progress towards using quantum walks for quantum computing and provides a framework for using fewer photons in combination with different degrees-of-freedom of photon to scale the number of qubits.

quant-ph↗

arXiv2025

Deterministic quantum teleportation of a path-encoded state using entangled photons

Quantum teleportation enables a way to transmit an arbitrary qubit state from one place to an other. A standard scheme for teleportation in optical setup involve three photons, an entangled photon pair and a photon carrying quantum state to be teleported. The interaction between the photons in the scheme makes quantum teleportation probabilistic. Here we demonstrate a deterministic teleportation of an arbitrary qubit state using only a polarization entangled photon pair in a linear optical setup. By introducing the path degree of freedom to one of the entangled photon and encoding the arbitrary qubit state into it, we demonstrate 100\% Bell State Measurement (BSM) outcome. This enables a deterministic teleportation of a qubit state in an optical scheme with high fidelity. We report an average teleportation fidelity of 88.00%. The dependency of fidelity on the visibility of single-photon interferometer used for path qubit state shows the possibility of further improving the fidelity of quantum teleportation.

quant-ph↗

arXiv2025

Emission from driven atoms in collective strong coupling with an optical cavity

We study self sustained cavity emission from driven atoms in collective strong coupling. The cavity emission occurs over a wide range of atom-cavity and drive laser detunings without any external input to the cavity mode. Second order correlation measurements ($g^2(τ)$), further reveal unanticipated phenomenon in the observed cavity emission such as, (a) damped oscillations at two frequencies and (b) significantly distinct $g^2(τ)$ for different polarization components. The intricate relation between cavity emission intensity, drive laser detuning and atom-cavity detunings is explained. A possible mechanism for the damped oscillations with two frequency components in $g^2(τ)$ is suggested. Measurements show the existence of two separate polarization decoupled mechanisms with distinct photon statistics, through which energy is transferred from the drive field to the cavity field. The statistical properties and mechanisms underlying cavity emission, as presented in this work, are expected to provide valuable insights for extending non-destructive detection techniques to the regime of collective strong coupling.

physics.atom-ph↗

arXiv2024

Detection of radiatively open systems using an optical cavity

We experimentally demonstrate a cavity-based detection scheme for a cold atomic ensemble with a radiatively open transition. Our method exploits the collective strong coupling of atoms to the cavity mode, which results in off-resonant probing of the atomic ensemble, leading to a dramatic reduction in losses from the detection cycle. We then show the viability of this frequency measurement for detecting a small number of atoms and molecules by theoretical modelling. Compared with the most commonly used fluorescence method, we show that the cavity-based scheme allows rapid and prolonged detection of the system's evolution with minimal destruction.

physics.atom-ph↗

arXiv2024

Cavity based non-destructive detection of photoassociation in a dark MOT

The photoassociation (PA) of rubidium dimer (Rb2) in a dark magneto-optic trap (MOT) is studied using atom-cavity collective strong coupling. This allows non-destructive detection of the molecule formation process as well as rapid and repeated interrogation of the atom-molecule system. The vacuum Rabi splitting (VRS) measurements from the bright MOT are carefully calibrated against equivalent measurements with fluorescence. Further loading rates in dark MOT are determined using VRS. This method provides a reliable, fast, and non-destructive detection scheme for ultracold molecules when the atoms are non-fluorescing using the free atoms coupled to a cavity.

physics.atom-ph↗

arXiv2023

Dynamic Fabry-Perot cavity stabilization technique for atom-cavity experiments

We present a stabilization technique developed to lock and dynamically tune the resonant frequency of a moderate finesse Fabry-Pérot (FP) cavity used in precision atom-cavity quantum electrodynamics (QED) experiments. Most experimental setups with active stabilization either operate at one fixed resonant frequency or use transfer cavities to achieve the ability to tune the resonant frequency of the cavity. In this work, we present a simple and cost-effective solution to actively stabilize an optical cavity while achieving a dynamic tuning range of over 100 MHz with a precision under 1 MHz. Our unique scheme uses a reference laser locked to an electro-optic modulator (EOM) shifted saturation absorption spectroscopy (SAS) signal. The cavity is locked to the PDH error signal obtained from the dip in the reflected intensity of this reference laser. Our setup provides the feature to efficiently tune the resonant frequency of the cavity by only changing the EOM drive without unlocking and re-locking either the reference laser or the cavity. We present measurements of precision control of the resonant cavity frequency and vacuum Rabi splitting (VRS) to quantify the stability achieved and hence show that this technique is suitable for a variety of cavity QED experiments.

physics.atom-ph↗