<?xml version="1.0" encoding="utf-8"?>
    <rss version="2.0">
      <channel xmlns:content="http://purl.org/rss/1.0/modules/content/">
        <title>Frontiers in Quantum Science and Technology | Quantum Engineering section | New and Recent Articles</title>
        <link>https://www.frontiersin.org/journals/quantum-science-and-technology/sections/quantum-engineering</link>
        <description>RSS Feed for Quantum Engineering section in the Frontiers in Quantum Science and Technology journal | New and Recent Articles</description>
        <language>en-us</language>
        <generator>Frontiers Feed Generator,version:1</generator>
        <pubDate>2026-05-10T20:33:17.225+00:00</pubDate>
        <ttl>60</ttl>
        <item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frqst.2025.1709220</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frqst.2025.1709220</link>
        <title><![CDATA[Optimizing ensemble NV− spin properties of fluorescent diamond microparticles by systematic low pressure high temperature annealing]]></title>
        <pubdate>2025-11-27T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Nicholas Nunn</author><author>Antonin Marek</author><author>Marco D. Torelli</author><author>Alex I. Smirnov</author><author>Olga A. Shenderova</author>
        <description><![CDATA[Low pressure high temperature annealing is a means for driving nitrogen and defect diffusion in diamond to reduce internal lattice damage without the need for technically complicated high-pressure cells. Herein, we perform a systematic time (5, 15, and 30 min) and temperature (1200 °C–1800 °C) study of effects of low-pressure high temperature annealing on photoluminescence, spin concentrations, and spin relaxation properties of NV centers in ca. 3 μm synthetic type 1b diamond particles. Annealing in the temperature range of ca. 1400 °C–1700 °C for even 5 min leads to a higher optically detected magnetic resonance contrast as compared to standard annealing at 900 °C for 2 h. Particles annealed at 1700 °C for 5 min exhibit a contrast close to about 13% as compared to about 9% for those annealed at 900 °C for 2 h. A reduction in the zero-field splitting strain parameter from E ≈ 4.5 MHz to ≈2.5 MHz and spectral linewidth from Δν ≈ 7 MHz to ≈4 MHz are observed even after 5 min annealing at 1700 °C. Improvements in these spectral parameters resulted in a roughly 2-fold reduction in the noise level of temperature monitoring experiment utilizing an ensemble of NV centers in the particles. Annealing in the temperature range of 1600 °C for 15 or 30 min or 1700 °C for 5 min resulted in NV T1 relaxation times approaching ca. 5 ms typically observed for bulk diamond. Quantitative electron paramagnetic resonance (EPR) allowed for estimations of thermal activation energies of paramagnetic center annihilation. Monitoring the primary defect concentration (P1 and other defects with half integer spins) and utilizing second order kinetic modeling, an activation energy of 3.63 ± 0.28 eV was estimated. Alternatively, using the NV half field EPR signal and first order kinetic modeling, a similar activation energy 3.89 ± 0.29 eV was estimated.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frqst.2025.1667545</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frqst.2025.1667545</link>
        <title><![CDATA[Fabrication of oriented NV center arrays in diamond via femtosecond laser writing and reorientation]]></title>
        <pubdate>2025-09-23T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Kai Klink</author><author>Andrew Raj Kirkpatrick</author><author>Yukihiro Tadokoro</author><author>Jonas Nils Becker</author><author>Shannon Singer Nicley</author>
        <description><![CDATA[IntroductionNitrogen-vacancy (NV) centers in diamond are widely recognized as highly promising solid-state quantum sensors due to their long room temperature coherence times and atomic-scale size, which enable exceptional sensitivity and nanoscale spatial resolution under ambient conditions. Ultrafast laser writing has demonstrated the deterministic spatial control of individual NV− centers, however, the resulting random orientation of the defect axis limits the magnetic field sensitivity and signal contrast.MethodsWe developed an all-optical approach for reorienting laser-written NV− centers to lie along a specific crystallographic axis using femtosecond laser annealing. The orientation is determined by polarization analysis, and the annealing and subsequent polarization analysis are repeated until the desired orientation is observed.ResultsOur method achieves deterministic alignment of NV− centers along the optical axis in (111)-oriented diamond substrates and allows selection between two observable orientation classes in (100)-oriented substrates. The reorientation preserves spatial ordering while producing uniform orientation across arrays of NV− centers.DiscussionThis approach enables scalable fabrication of orientation-controlled NV− arrays, and paves the way for scalable, high performance quantum devices based on orientation-controlled NV− centers.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frqst.2025.1526469</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frqst.2025.1526469</link>
        <title><![CDATA[Phase-dependent transparency in a two-level system with applications to all-optical switching]]></title>
        <pubdate>2025-08-06T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Aneesh Ramaswamy</author><author>Svetlana A. Malinovskaya</author>
        <description><![CDATA[The phenomenon of transparency, conventionally studied in three and higher level atomic systems, is extended to the case of a two-level system (TLS), where we use a semiclassical framework to describe the transparent propagation of classical fields in a medium of TLS scatterers. We demonstrate a new form of transparency with fast pulses, accounting for the initial state of the TLS, which we call phase-dependent transparency. Using the phenomenon of photon locking, we showed that TLSs initialized in maximum coherence states exhibit transparency to resonant fields when there is phase-matching between the phase of the atomic coherence and that of the probe field. An application to the problem of all-optical switching is also discussed, where on-demand transmission is generated by controlling the relative phase between a π/2 pump pulse and the transmitted probe pulse.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frqst.2025.1546480</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frqst.2025.1546480</link>
        <title><![CDATA[The refractive index of a single three-level atom experienced by a single photon]]></title>
        <pubdate>2025-04-29T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Jacob Emerick</author><author>Anil K. Patnaik</author><author>Yuri Rostovtsev</author>
        <description><![CDATA[We study the propagation of a quantum field composed of a few photons interacting with a three-level Λ-atom driven by a coherent classical field. The quantum field acquires a phase shift, which can be interpreted as a dispersion effect on the photon wave packet and described by the refractive index for quantum fields down to the single-photon level. In this paper, we demonstrate that the phases acquired by quantum fields depend on the number of photons in the quantum states. Notably, the phases differ between single- and two-photon states, enabling the separation of multiphoton states. This finding highlights new applications related to the dispersion of three-level atoms, which are important in advancing quantum information processing and enhancing quantum communication technologies. The results are crucial for long-distance quantum communication and hold potential for developing quantum field-based linear devices such as beam splitters, lenses, and quantum prisms capable of separating different components of quantum fields. The findings can have interesting applications for manipulating and assembling of multiphoton entanglement states.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frqst.2025.1540695</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frqst.2025.1540695</link>
        <title><![CDATA[Optimal control of a Bose-Einstein condensate in an opticallattice: the non-linear and two-dimensional cases]]></title>
        <pubdate>2025-02-03T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>E. Dionis</author><author>B. Peaudecerf</author><author>S. Guérin</author><author>D. Guéry-Odelin</author><author>D. Sugny</author>
        <description><![CDATA[We numerically study the optimal control of an atomic Bose-Einstein condensate in an optical lattice. We present two generalizations of the gradient-based algorithm, GRAPE, in the non-linear case and for a two-dimensional lattice. We show how to construct such algorithms from Pontryagin’s maximum principle. A wide variety of target states can be achieved with high precision by varying only the laser phases setting the lattice position. We discuss the physical relevance of the different results and the future directions of this work.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frqst.2023.1135816</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frqst.2023.1135816</link>
        <title><![CDATA[Shortcuts to adiabaticity in a fast controlled-phase gate in superconducting quantum circuits]]></title>
        <pubdate>2023-03-15T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Jia-Xin Li</author><author>F. A. Cárdenas-López</author><author>Xi Chen</author>
        <description><![CDATA[Based on renewed interest in the shortcut-to-adiabaticity techniques in quantum control, we propose a reverse-engineering approach to modulate the longitudinal coupling between a pair of two-level systems with a quantized single-mode resonator. This allows us to suppress the unwanted transitions in the time-evolution operator such that the system dynamics resemble a controlled-phase gate acting in the qubit subspace at the nanosecond scale. The reduced gating time mitigates the detrimental effect produced by the loss mechanisms in all aspects. Moreover, we present a possible experimental implementation based on superconducting quantum circuits. Our work further demonstrates the versatility of the reverse-engineering method to enhance quantum protocols based on circuit quantum electrodynamic architecture.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frqst.2023.1128576</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frqst.2023.1128576</link>
        <title><![CDATA[NP-hard but no longer hard to solve? Using quantum computing to tackle optimization problems]]></title>
        <pubdate>2023-02-23T00:00:00Z</pubdate>
        <category>Perspective</category>
        <author>Rhonda Au-Yeung</author><author>Nicholas Chancellor</author><author>Pascal Halffmann</author>
        <description><![CDATA[In the last decade, public and industrial research funding has moved quantum computing from the early promises of Shor’s algorithm through experiments to the era of noisy intermediate scale quantum devices (NISQ) for solving real-world problems. It is likely that quantum methods can efficiently solve certain (NP-) hard optimization problems where classical approaches fail. In our perspective, we examine the field of quantum optimization, that is, solving optimization problems using quantum computers. We provide an entry point to quantum optimization for researchers from each topic, optimization or quantum computing, by demonstrating advances and obstacles with a suitable use case. We give an overview on problem formulation, available algorithms, and benchmarking. Although we show a proof-of-concept rather than a full benchmark between classical and quantum methods, this gives an idea of the current quality and capabilities of quantum computers for optimization problems. All observations are incorporated in a discussion on some recent quantum optimization breakthroughs, current status, and future directions.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frqst.2022.1078597</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frqst.2022.1078597</link>
        <title><![CDATA[Phase-dependent strategy to mimic quantum phase transitions]]></title>
        <pubdate>2023-01-12T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Yuan Zhou</author><author>Lian-Zhen Cao</author><author>Qing-Lan Wang</author><author>Chang-Sheng Hu</author><author>Zhu-Cheng Zhang</author><author>Wei Xiong</author>
        <description><![CDATA[This study proposes a hybrid quantum system of an ensemble of collective spins coupled to a surface acoustic wave (SAW) cavity through a sideband design. Assisted by a dichromatic optical drive with a phase-dependent control, this spin ensemble can effectively mimic different types of long-range Lipkin–Meshkov–Glick (LMG) interactions and then undergo quantum phase transitions (QPTs) due to phase-induced spontaneous symmetry breaking (SSB). In addition, this phase-controlled scheme also ensures the dynamical preparation of the spin-squeezed state (SSS), which may be a useful application in quantum measurement. This study is a fresh attempt at quantum manipulation based on acoustic control and also provides a promising route toward useful applications in quantum information processing, especially the adiabatic preparation of multiparticle-entangled ground states via QPTs; i.e., the Greenberger–Horne–Zeilinger (GHZ) or W-type states.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frqst.2022.1091691</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frqst.2022.1091691</link>
        <title><![CDATA[Application perspective of cavity optomechanical system]]></title>
        <pubdate>2023-01-09T00:00:00Z</pubdate>
        <category>Perspective</category>
        <author>Huanying Sun</author><author>Yulong Liu</author><author>Tiefu Li</author>
        <description><![CDATA[Cavity optomechanical systems are demonstrating diverse applications in sensing and transduction, profiting from advances in related theories and experiments, which also promotes quantum research based on them. Here, we first briefly introduce typical applications of cavity optomechanical systems and some of our recent progress in this field and then discuss the potential of cavity optomechanical systems for exploring fundamental questions in quantum theory and the challenges encountered in current developments. Cavity optomechanical systems will play a vital role in quantum computing and quantum information and will enrich the quantum toolbox, particularly in quantum interfaces and quantum memory.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frqst.2022.1026025</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frqst.2022.1026025</link>
        <title><![CDATA[Experimental validation of the Kibble-Zurek mechanism on a digital quantum computer]]></title>
        <pubdate>2022-10-25T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Santiago Higuera-Quintero</author><author>Ferney J. Rodríguez</author><author>Luis Quiroga</author><author>Fernando J. Gómez-Ruiz</author>
        <description><![CDATA[The Kibble-Zurek mechanism (KZM) captures the essential physics of nonequilibrium quantum phase transitions with symmetry breaking. KZM predicts a universal scaling power law for the defect density which is fully determined by the system’s critical exponents at equilibrium and the quenching rate. We experimentally tested the KZM for the simplest quantum case, a single qubit under the Landau-Zener evolution, on an open access IBM quantum computer (IBM-Q). We find that for this simple one-qubit model, experimental data validates the central KZM assumption of the adiabatic-impulse approximation for a well isolated qubit. Furthermore, we report on extensive IBM-Q experiments on individual qubits embedded in different circuit environments and topologies, separately elucidating the role of crosstalk between qubits and the increasing decoherence effects associated with the quantum circuit depth on the KZM predictions. Our results strongly suggest that increasing circuit depth acts as a decoherence source, producing a rapid deviation of experimental data from theoretical unitary predictions.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frqst.2022.1007756</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frqst.2022.1007756</link>
        <title><![CDATA[Bistable carbon-vacancy defects in h-BN]]></title>
        <pubdate>2022-09-30T00:00:00Z</pubdate>
        <category>Original Research</category>
        <author>Song Li</author><author>Adam Gali</author>
        <description><![CDATA[Single-photon emitters in hexagonal boron nitride have been extensively studied recently. Although unambiguous identification of the emitters is still under intense research, carbon-related defects are believed to play a vital role for the emitter producing zero-phonon lines in the range of 1.6–2.2 eV. In this study, we systematically investigate two configurations of carbon-vacancy defects, VNCB and CNVB, by means of density functional theory calculations. We calculated the reaction barrier energies from one defect to the other to determine relative stability. We find that the barrier energies are charge dependent, and CNVB could easily transform to VNCB in neutral- and positive-charge states while it is stable when negatively charged. Formation energy calculations show that the VNCB is the dominant defect over CNVB. However, neither VNCB nor CNVB has suitable fluorescence spectra that could reproduce the observed ones. Our results indicate that the origin of the 1.6-to-2.2-eV emitters should be other carbon-related configurations.]]></description>
      </item><item>
        <guid isPermaLink="true">https://www.frontiersin.org/articles/10.3389/frqst.2022.1029525</guid>
        <link>https://www.frontiersin.org/articles/10.3389/frqst.2022.1029525</link>
        <title><![CDATA[Specialty Grand Challenge: Quantum engineering]]></title>
        <pubdate>2022-09-23T00:00:00Z</pubdate>
        <category>Specialty Grand Challenge</category>
        <author>Juan José García-Ripoll</author>
        <description></description>
      </item>
      </channel>
    </rss>