arXiv subjects

Mahmood Sabooni

Publications and source records attributed to Mahmood Sabooni.

11 recordsLinked to original sources

arXiv2026

Steady States of a Single Trapped-Ion Spin Coupled to an Engineered Non-Markovian Bath

Quantum simulation of open quantum systems offers a pathway towards better understanding various non-equilibrium physics that would otherwise be challenging to study. While most open quantum systems studied are modeled as being memory-less (obeying the Markov approximation), real baths generally are influenced by the system-bath interaction, and some systems existing in structured non-Markovian environments can display novel behavior as a result. Here we utilize a trapped ion quantum simulator to simulate a single spin-$1/2$ driven-dissipative system with a non-Markovian dissipation channel, and experimentally compare steady-states to those from an analogous Markovian bath. We observe that a non-Markovian dissipative channel can shift the steady-state even for a single qubit, to a regime inaccessible for Markovian dissipation. The techniques used here are compatible with many-body extensions of the model, which can not be simulated efficiently on a classical computer in general. Our work also opens up new possibilities in quantum reservoir engineering beyond the Markovian regime.

quant-ph↗

arXiv2025

A Room-Temperature Extreme High Vacuum System for Trapped-Ion Quantum Information Processing

We present a room-temperature Extreme High Vacuum (XHV) system engineered to support the long-duration operation of a trapped-ion quantum processor. Background-gas collisions impose limitations on trapped-ion performance and scalability by interrupting algorithmic execution and, in some cases, ejecting ions from the trap. Using molecular-flow simulations, we optimize the chamber geometry, conductance pathways, and pumping configuration to maximize the effective pumping speed at the ion location. We perform high-temperature heat treatment of stainless steel vacuum components to achieve the desired outgassing rate, guided by quantitative relations of bulk diffusive processes, allowing us to reduce the $\mathrm{H_2}$ outgassing load to the $10^{-15}\,\mathrm{mbar\,l\,s^{-1}\,cm^{-2}}$ level. The final pressure in our chamber, measured by a hot cathode gauge, is $1.5\times10^{-12}\,\mathrm{mbar}$, corresponding to the gauge's measurement limit. We measure the local pressure at the ion location by observing collision-induced reordering events in a long ion chain of mixed-isotope Yb$^+$. From the observed reordering frequency, we extract the average interval between collisions to be $(1.9 \pm 0.1)\,\mathrm{hrs/ion}$. This corresponds to a local pressure of $(3.9 \pm 0.3)\times10^{-12}\,\mathrm{mbar}$ at the ion location, assuming that all collisions arise from background H$_2$ molecules at room temperature. Our demonstration extends the continuous operation time of a quantum processor while maintaining the simplicity of a room-temperature system that does not require cryogenic apparatus.

quant-ph↗

arXiv2020

A naturally trapped rare-earth doped solid-state superradiant laser clock

We propose a solid-state based superradiance laser which is almost insensitive to the cavity mirror vibration. Therefore, it can compete with the best frequency-stable local oscillators. The long coherence time and the large optical density of rare-earth-ions (REIs) doped solids are employed to find a regime to demonstrate a steady-state laser emission with linewidth smaller than the atomic decay rate. The experimental parameters are discussed and intracavity photon number and laser linewidth are calculated based on the mean-field theory. A procedure for measuring absolute laser linewidth is proposed.

quant-ph↗

arXiv2020

Broadband and efficient Quantum Memory Using ac Stark Gradient Echo Memory

A quantum state light-storage, using a virtual magnetic field through the ac Stark effect is proposed to combine the high overall storage efficiency and large bandwidth employing room temperature atomic vapor. In this approach, which was called the ac Stark Gradient Echo Memory (ASGEM), it has been shown the possibility to employ about a nanosecond ac Stark pulse far detuned (about 127 THz) from D1 line of rubidium and create an atomic media with the possibility to store a photon with about a GHz bandwidth with storage and retrieval efficiency of more than 90%. A contour plot of efficiency as a function of gradient field strength and optical depth, based on three-level Maxwell- Bloch equations, simulated for a better understanding of experimental parameter optimization.

quant-ph↗

arXiv2019

Photon echoes in optically dense media

Coherent nonlinear multi-pulse processes, nonlinear waves and echo effects in resonant media are the topical problems of modern optics and important tools of coherent spectroscopy and quantum information science. We generalize the McCall-Hahn area theorem to the formation of an arbitrary photon echo generated during the multi-pulse excitation of the optically dense resonant media. The derived theorem made it possible to reveal the nonlinear mechanism of generation and evolution of the photon echo signals inside the media after a two-pulse excitation. We find that a series of self-reviving echo signals with total area of $2π$ or $0π$ is excited and propagates in the media depth, with each pulse having an individual area less than $π$. The resulting echo pulse train is a new alternative to the well-known soliton or breather. The developed pulse-area approach paves the way for more precise coherent spectroscopy, studies of different photon echo signals and quantum control of light pulses in the optically dense media.

quant-ph↗

arXiv2015

Wave propagation in birefringent materials with off axis absorption or gain

The polarization direction of an electromagnetic field changes and eventually reaches a steady state when propagating through a birefringent material with off axis absorption or gain. The steady state orientation direction depends on the magnitude of the absorption (gain) and the phase retardation rate. The change in the polarization direction is experimentally demonstrated in weakly doped ($0.05\%$) Pr$^{3+}$:Y$_2$SiO$_5$ crystals, where the light polarization, if initially aligned along the most strongly absorbing principal axis, gradually switch to a much less absorbing polarization state during the propagation. This means that the absorption coefficient, $α$, in birefringent materials generally varies with length. This is important for, e.g., laser crystal gain media, highly absorbing and narrow band spectral filters and quantum memories.

physics.atom-ph↗

arXiv2013

Three orders of magnitude cavity-linewidth narrowing by slow light in a rare-earth-ion-doped crystal cavity

Three orders of magnitude cavity-linewidth narrowing in a rare-earth-ion-doped crystal cavity, induced by strong intra-cavity dispersion caused by off-resonant interaction with dopant ions is demonstrated. The strong dispersion is created by semi-permanent but rapidly reprogrammable changes of the rare earth absorption profiles using optical pumping techniques. Several cavity modes are shown within the spectral transmission window. Potential applications are discussed.

quant-ph↗

arXiv2013

Spectral Engineering of Slow Light, Cavity Line Narrowing, and Pulse Compression

More than 4 orders of magnitude of cavity-linewidth narrowing in a rare-earth-ion-doped crystal cavity, emanating from strong intracavity dispersion caused by off-resonant interaction with dopant ions, is demonstrated. The dispersion profiles are engineered using optical pumping techniques creating significant semipermanent but reprogrammable changes of the rare-earth absorption profiles. Several cavity modes are shown within the spectral transmission window. Several possible applications of this phenomenon are discussed.

quant-ph↗

arXiv2013

Cavity enhanced storage - preparing for high efficiency quantum memories

Cavity assisted quantum memory storage has been proposed [PRA 82, 022310 (2010), PRA 82, 022311 (2010)] for creating efficient (close to unity) quantum memories using weakly absorbing materials. Using this approach we experimentally demonstrate a significant (about 20-fold) enhancement in quantum memory efficiency compared to the no cavity case. A strong dispersion originating from absorption engineering inside the cavity was observed, which directly affect the cavity line-width. A more than 3 orders of magnitude reduction of cavity mode spacing and cavity line-width from GHz to MHz was observed. We are not aware of any previous observation of several orders of magnitudes cavity mode spacing and cavity line-width reduction due to slow light effects.

quant-ph↗

arXiv2013

Efficient quantum memory using a weakly absorbing sample

A light-storage experiment with a total (storage and retrieval) efficiency $η=58 \pm 5%$ is carried out by enclosing a sample, with a single pass absorption of 10%, in an impedance-matched cavity. The experiment is carried out using the Atomic Frequency Comb (AFC) technique in a praseodymium-doped crystal ($0.05%Pr^{3+}:Y_2SiO_5$) and the cavity is created by reflection coating the crystal surfaces. The AFC technique has previously by far demonstrated the highest multi-mode capacity of all quantum memory concepts tested experimentally. We claim that the present work shows that it is realistic to create efficient, on-demand, long storage time AFC memories.

quant-ph↗

arXiv2011

Hyperfine characterization and coherence lifetime extension in Pr3+:La2(WO4)3

Rare-earth ions in dielectric crystals are interesting candidates for storing quantum states of photons. A limiting factor on the optical density and thus the conversion efficiency is the distortion introduced in the crystal by doping elements of one type into a crystal matrix of another type. Here, we investigate the system Pr3+:La2(WO4)3, where the similarity of the ionic radii of Pr and La minimizes distortions due to doping. We characterize the praseodymium hyperfine interaction of the ground state (3H4) and one excited state (1D2) and determine the spin Hamiltonian parameters by numerical analysis of Raman-heterodyne spectra, which were collected for a range of static external magnetic field strengths and orientations. On the basis of a crystal field analysis, we discuss the physical origin of the experimentally determined quadrupole and Zeeman tensor characteristics. We show the potential for quantum memory applications by measuring the spin coherence lifetime in a magnetic field that is chosen such that additional magnetic fields do not shift the transition frequency in first order. Experimental results demonstrate a spin coherence lifetime of 158 ms - almost three orders of magnitude longer than in zero field.

quant-ph↗