Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We demonstrate dispersive readout of the spin of an ensemble of nitrogen-vacancy centers in a high-quality dielectric microwave resonator at room temperature. The spin state is inferred from the reflection phase of a microwave signal probing the resonator. Time-dependent tracking of the spin state is demonstrated, and is employed to measure the <jats:italic>T</jats:italic> <jats:sub>1</jats:sub> relaxation time of the spin ensemble. Dispersive readout provides a microwave interface to solid state spins, translating a spin signal into a microwave phase shift. We estimate that its sensitivity can outperform optical readout schemes, owing to the high accuracy achievable in a measurement of phase. The scheme is moreover applicable to optically inactive spin defects and it is non-destructive, which renders it insensitive to several systematic errors of optical readout and enables the use of quantum feedback.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Interest in building dedicated quantum information science and engineering (QISE) education programs has greatly expanded in recent years. These programs are inherently convergent, complex, often resource intensive and likely require collaboration with a broad variety of stakeholders. In order to address this combination of challenges, we have captured ideas from many members in the community. This manuscript not only addresses policy makers and funding agencies (both public and private and from the regional to the international level) but also contains needs identified by industry leaders and discusses the difficulties inherent in creating an inclusive QISE curriculum. We report on the status of eighteen post-secondary education programs in QISE and provide guidance for building new programs. Lastly, we encourage the development of a comprehensive strategic plan for quantum education and workforce development as a means to make the most of the ongoing substantial investments being made in QISE.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The unique features of quantum theory offer a powerful new paradigm for information processing. Translating these mathematical abstractions into useful algorithms and applications requires quantum systems with significant complexity and sufficiently low error rates. Such quantum systems must be made from robust hardware that can coherently store, process, and extract the encoded information, as well as possess effective quantum error correction (QEC) protocols to detect and correct errors. Circuit quantum electrodynamics (cQED) provides a promising hardware platform for implementing robust quantum devices. In particular, bosonic encodings in cQED that use multi-photon states of superconducting cavities to encode information have shown success in realizing hardware-efficient QEC. Here, we review recent developments in the theory and implementation of QEC with bosonic codes and report the progress made toward realizing fault-tolerant quantum information processing with cQED devices.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Light scalar dark matter (DM) with scalar couplings to matter is expected within several scenarios to induce variations in the fundamental constants of nature. Such variations can be searched for, among other ways, via atomic spectroscopy. Sensitive atomic observables arise primarily due to possible changes in the fine-structure constant or the electron mass. Most of the searches to date have focused on slow variations of the constants (i.e. modulation frequencies &lt;1 Hz). In a recent experiment (2019 <jats:italic>Phys. Rev. Lett.</jats:italic> <jats:bold>123</jats:bold> 141102) called weekend relaxion-search laboratory (WReSL), we reported on a direct search for rapid variations in the radio-frequency band. Such a search is particularly motivated within a class of relaxion DM models. We discuss the WReSL experiment, report on progress toward improved measurements of rapid fundamental constant variations, and discuss the planned extension of the work to molecules, in which rapid variations of the nuclear mass can be sensitively searched for.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The low-energy, long-lived isomer in <jats:sup>229</jats:sup>Th, first studied in the 1970s as an exotic feature in nuclear physics, continues to inspire a multidisciplinary community of physicists. It has stimulated innovative ideas and studies that expand the understanding of atomic and nuclear structure of heavy elements and of the interaction of nuclei with bound electrons and coherent light. Using the nuclear resonance frequency, determined by the strong and electromagnetic interactions inside the nucleus, it is possible to build a highly precise nuclear clock that will be fundamentally different from all other atomic clocks based on resonant frequencies of the electron shell. The nuclear clock will open opportunities for highly sensitive tests of fundamental principles of physics, particularly in searches for violations of Einstein’s equivalence principle and for new particles and interactions beyond the standard model. It has been proposed to use the nuclear clock to search for variations of the electromagnetic and strong coupling constants and for dark matter searches. The <jats:sup>229</jats:sup>Th nuclear optical clock still represents a major challenge in view of the tremendous gap of nearly 17 orders of magnitude between the present uncertainty in the nuclear transition frequency (about 0.2 eV, corresponding to ∼48 THz) and the natural linewidth (in the mHz range). Significant experimental progress has been achieved in recent years, which will be briefly reviewed. Moreover, a research strategy will be outlined to consolidate our present knowledge about essential <jats:sup>229m</jats:sup>Th properties, to determine the nuclear transition frequency with laser spectroscopic precision, realize different types of nuclear clocks and apply them in precision frequency comparisons with optical atomic clocks to test fundamental physics. Two avenues will be discussed: laser-cooled trapped <jats:sup>229</jats:sup>Th ions that allow experiments with complete control on the nucleus–electron interaction and minimal systematic frequency shifts, and Th-doped solids enabling experiments at high particle number and in different electronic environments.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We study heating of motional modes of a single ion and of extended ion crystals trapped in a linear radio frequency (rf) Paul trap with a precision of <jats:inline-formula> <jats:tex-math><?CDATA ${\Delta}\dot {\bar{n}}\approx 0.1$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi mathvariant="normal">Δ</mml:mi> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> <mml:mo>̄</mml:mo> </mml:mover> </mml:mrow> </mml:mrow> <mml:mo>̇</mml:mo> </mml:mover> </mml:mrow> <mml:mo>≈</mml:mo> <mml:mn>0.1</mml:mn> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="qstabee99ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> phonons s<jats:sup>−1</jats:sup>. Single-ion axial and radial heating rates are consistent and electric field noise has been stable over the course of four years. At a secular frequency of <jats:italic>ω</jats:italic> <jats:sub>sec</jats:sub> = 2<jats:italic>π</jats:italic> × 620 kHz, we measure <jats:inline-formula> <jats:tex-math><?CDATA $\dot {\bar{n}}=0.56\left(6\right)$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> <mml:mo>̄</mml:mo> </mml:mover> </mml:mrow> </mml:mrow> <mml:mo>̇</mml:mo> </mml:mover> </mml:mrow> <mml:mo>=</mml:mo> <mml:mn>0.56</mml:mn> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mrow> <mml:mn>6</mml:mn> </mml:mrow> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="qstabee99ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> phonons s<jats:sup>−1</jats:sup> per ion for the center-of-mass (com) mode of linear chains of up to 11 ions and observe no significant heating of the out-of-phase (oop) modes. By displacing the ions away from the nodal line, inducing excess micromotion, rf noise heats the com mode quadratically as a function of radial displacement <jats:italic>r</jats:italic> by <jats:inline-formula> <jats:tex-math><?CDATA $\dot {\bar{n}}\left(r\right)/{r}^{2}=0.89\left(4\right)$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mrow> <mml:mover accent="true"> <mml:mrow> <mml:mi>n</mml:mi> </mml:mrow> <mml:mo>̄</mml:mo> </mml:mover> </mml:mrow> </mml:mrow> <mml:mo>̇</mml:mo> </mml:mover> </mml:mrow> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mrow> <mml:mi>r</mml:mi> </mml:mrow> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> <mml:mo>/</mml:mo> <mml:msup> <mml:mrow> <mml:mi>r</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> <mml:mo>=</mml:mo> <mml:mn>0.89</mml:mn> <mml:mrow> <mml:mo stretchy="false">(</mml:mo> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="qstabee99ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> phonons s<jats:sup>−1</jats:sup> <jats:italic>μ</jats:italic>m<jats:sup>−2</jats:sup> per ion, while the oop modes are protected from rf-noise induced heating in linear chains. By changing the quality factor of the resonant rf circuit from <jats:italic>Q</jats:italic> = 542 to <jats:italic>Q</jats:italic> = 204, we observe an increase of rf noise by a factor of up to 3. We show that the rf-noise induced heating of motional modes of extended crystals also depends on the symmetry of the crystal and of the mode itself. As an example, we consider several 2D and 3D crystal configurations. Heating rates of up to 500 ph s<jats:sup>−1</jats:sup> are observed for individual modes, giving rise to a total kinetic energy increase and thus a fractional time dilation shift of up to −0.3 × 10<jats:sup>−18</jats:sup> s<jats:sup>−1</jats:sup> of the total system. In addition, we detail how the excitation probability of the individual ions is reduced and decoherence is increased due to the Debye–Waller effect.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Dark matter (DM) is one of the biggest open questions in physics today. It is known that it interacts gravitationally with luminous matter, so accelerometer-based searches are inherently interesting. In this article we present recent (and future) searches for DM candidates such as feebly interacting matter trapped inside the Earth, scalar-matter domain walls and axion quark nuggets, with accelerometer networks and give an outlook of how new atomic-interferometry-based accelerometer networks could support DM searches.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Frequency-resolved photon correlations have proven to be a useful resource to unveil nonlinearities hidden in standard observables such as the spectrum or the standard (color-blind) photon correlations. In this manuscript, we analyze the frequency-resolved correlations of the photons being emitted from an <jats:italic>optomechanical</jats:italic> system where light is nonlinearly coupled to the quantized motion of a mechanical mode of a resonator, but where the quantum nonlinear response is typically hard to evidence. We present and unravel a rich landscape of frequency-resolved correlations, and discuss how the time-delayed correlations can reveal information about the dynamics of the system. We also study the dependence of correlations on relevant parameters such as the single-photon coupling strength, the filtering linewidth, or the thermal noise in the environment. This enriched understanding of the system can trigger new experiments to probe nonlinear phenomena in optomechanics, and provide insights into dynamics of generic nonlinear systems.</jats:p>