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Philippe Goldner

Publications and source records attributed to Philippe Goldner.

At least 55 records · Page 3Linked to original sources
arXiv2020

Molecule-based coherent light-spin interfaces for quantum information processing -- optical spin state polarization in a binuclear Europium complex

The success of the emerging field of solid-state optical quantum information processing (QIP) critically depends on the access to resonant optical materials. Rare-earth ions (REIs) are suitable candidates for QIP protocols due to their extraordinary photo-physical and magnetic quantum properties such as long optical and spin coherence lifetimes ($T_2$). However, molecules incorporating REIs, despite having advantageous properties such as atomically exact quantum tunability, inherent scalability, and large portability, have not yet been studied for QIP applications. As a first testimony of the usefulness of REI molecules for optical QIP applications, we demonstrate in this study that narrow spectral holes can be burned in the inhomogeneously broadened $^5$D$_0\to^7$F$_0$ optical transition of a binuclear Eu(III) complex, rendering a homogeneous linewidth ($Γ_h$) = 22 $\pm$ 1 MHz, which translates as $T_2 = 14.5$ $\pm$ 0.7 ns at 1.4 K. Moreover, long-lived spectral holes are observed, demonstrating efficient polarization of Eu(III) ground state nuclear spins, a fundamental requirement for all-optical spin initialization and addressing. These results elucidate the usefulness of REI-based molecular complexes as versatile coherent light-spin interfaces for applications in quantum communications and processing.

quant-ph↗
arXiv2020

A Frequency-Multiplexed Coherent Electro-Optic Memory in Rare Earth Doped Nanoparticles

Quantum memories for light are essential components in quantum technologies like long-distance quantum communication and distributed quantum computing. Recent studies have shown that long optical and spin coherence lifetimes can be observed in rare earth doped nanoparticles, opening exciting possibilities over bulk materials e.g. for enhancing coupling to light and other quantum systems, and material design. Here, we report on coherent light storage in Eu$^{3+}$:Y$_2$O$_3$ nanoparticles using the Stark Echo Modulation Memory (SEMM) quantum protocol. We first measure a nearly constant Stark coefficient of 50 kHz/(V/cm) across a bandwidth of 15 GHz, which is promising for broadband operation. Storage of light using SEMM is then demonstrated for times up to 40 $μ$s. Pulses with two different frequencies are also stored, confirming frequency-multiplexing capability, and are used to demonstrate the memory high phase fidelity.

quant-ph↗
arXiv2020

Optical spin-wave storage in a solid-state hybridized electron-nuclear spin ensemble

Solid-state impurity spins with optical control are currently investigated for quantum networks and repeaters. Among these, rare-earth-ion doped crystals are promising as quantum memories for light, with potentially long storage time, high multimode capacity, and high bandwidth. However, with spins there is often a tradeoff between bandwidth, which favors electronic spin, and memory time, which favors nuclear spins. Here, we present optical storage experiments using highly hybridized electron-nuclear hyperfine states in $^{171}$Yb$^{3+}$:Y$_2$SiO$_5$, where the hybridization can potentially offer both long storage time and high bandwidth. We reach a storage time of 1.2 ms and an optical storage bandwidth of 10 MHz that is currently only limited by the Rabi frequency of the optical control pulses. The memory efficiency in this proof-of-principle demonstration was about 3%. The experiment constitutes the first optical storage using spin states in any rare-earth ion with electronic spin. These results pave the way for rare-earth based quantum memories with high bandwidth, long storage time and high multimode capacity, a key resource for quantum repeaters.

quant-ph↗
arXiv2020

Dynamic control of Purcell enhanced emission of erbium ions in nanoparticles

The interaction of single quantum emitters with an optical cavity enables the realization of efficient spin-photon interfaces, an essential resource for quantum networks. The dynamical control of the spontaneous emission rate of quantum emitters in cavities has important implications in quantum technologies, e.g. for shaping the emitted photons waveform, for generating quantum entanglement, or for driving coherently the optical transition while preventing photon emission. Here we demonstrate the dynamical control of the Purcell enhanced emission of a small ensemble of erbium ions doped into nanoparticles. By embedding the doped nanoparticles into a fully tunable high finesse fiber based optical microcavity, we show that we can tune the cavity on- and out of-resonance by controlling its length with sub-nanometer precision, on a time scale more than two orders of magnitude faster than the natural lifetime of the erbium ions. This allows us to shape in real time the Purcell enhanced emission of the ions and to achieve full control over the emitted photons' waveforms. This capability opens prospects for the realization of efficient nanoscale quantum interfaces between solid-state spins and single telecom photons with controllable waveform, and for the realization of quantum gates between rare-earth ion qubits coupled to an optical cavity.

quant-ph↗
arXiv2019

Coherence Time Extension by Large Scale Optical Spin Polarization in a Rare-Earth Doped Crystal

Optically addressable spins are actively investigated in quantum communication, processing and sensing. Optical and spin coherence lifetimes, which determine quantum operation fidelity and storage time, are often limited by spin-spin interactions, which can be decreased by polarizing spins in their lower energy state using large magnetic fields and/or mK range temperatures. Here, we show that optical pumping of a small fraction of ions with a fixed frequency laser, coupled with spin-spin interactions and spin diffusion, leads to substantial spin polarization in a paramagnetic rare earth doped crystal, $^{171}$Yb$^{3+}$:YSO. Indeed, up to more than 90 % spin polarizations have been achieved at 2 K and zero magnetic field. Using this spin polarization mechanism, we furthermore demonstrate an increase in optical coherence lifetime from 0.3 ms to 0.8 ms, due to a strong decrease in spin-spin interactions. This effect opens the way to new schemes for obtaining long optical and spin coherence lifetimes in various solid-state systems such as ensembles of rare earth ions or color centers in diamond, which is of interest for a broad range of quantum technologies.

cond-mat.mtrl-sci↗
arXiv2019

Extending Phenomenological Crystal-Field Methods to $C_1$ Point-Group Symmetry: Characterization of the Optically-Excited Hyperfine Structure of $^{167}$Er$^{3+}$:Y$_2$SiO$_5$

We show that crystal-field calculations for $C_1$ point-group symmetry are possible, and that such calculations can be performed with sufficient accuracy to have substantial utility for rare-earth based quantum information applications. In particular, we perform crystal-field fitting for a C$_1$-symmetry site in $^{167}$Er$^{3+}$:Y$_2$SiO$_5$. The calculation simultaneously includes site-selective spectroscopic data up to 20,000 cm$^{-1}$, rotational Zeeman data, and ground- and excited-state hyperfine structure determined from high-resolution Raman-heterodyne spectroscopy on the 1.5 $μ$m telecom transition. We achieve an agreement of better than 50 MHz for assigned hyperfine transitions. The success of this analysis opens the possibility of systematically evaluating the coherence properties, as well as transition energies and intensities, of any rare-earth ion doped into Y$_2$SiO$_5$ .

physics.atom-ph↗
arXiv2019

High-cooperativity coupling of a rare-earth spin ensemble to a superconducting resonator using yttrium orthosilicate as a substrate

Yttrium orthosilicate (Y$_2$SiO$_5$, or YSO) has proved to be a convenient host for rare-earth ions used in demonstrations of microwave quantum memories and optical memories with microwave interfaces, and shows promise for coherent microwave--optical conversion owing to its favourable optical and spin properties. The strong coupling required by such microwave applications could be achieved using superconducting resonators patterned directly on Y$_2$SiO$_5$, and hence we investigate here the use of Y$_2$SiO$_5$ as an alternative to sapphire or silicon substrates for superconducting hybrid device fabrication. A NbN resonator with frequency 6.008 GHz and low power quality factor $Q \approx 400000$ was fabricated on a Y$_2$SiO$_5$ substrate doped with isotopically enriched Nd$^{145}$. Measurements of dielectric loss yield a loss-tangent $\tanδ= 4 \times 10^{-6}$, comparable to sapphire. Electron spin resonance (ESR) measurements performed using the resonator show the characteristic angular dependence expected from the anisotropic Nd$^{145}$ spin, and the coupling strength between resonator and electron spins is in the high cooperativity regime ($C = 30$). These results demonstrate Y$_2$SiO$_5$ as an excellent substrate for low-loss, high-Q microwave resonators, especially in applications for coupling to optically-accessible rare earth spins.

cond-mat.mes-hall↗
arXiv2018

Spectroscopic study of hyperfine properties in $^{171}$Yb$^{3+}$:Y$_2$SiO$_5$

Rare-earth ion doped crystals are promising systems for quantum communication and quantum information processing. In particular, paramagnetic rare-earth centres can be utilized to realize quantum coherent interfaces simultaneously for optical and microwave photons. In this article, we study hyperfine and magnetic properties of a Y$_2$SiO$_5$ crystal doped with $^{171}$Yb$^{3+}$ ions. This isotope is particularly interesting since it is the only rare--earth ion having electronic spin $S=\frac{1}{2}$ and nuclear spin $I=\frac{1}{2}$, which results in the simplest possible hyperfine level structure. In this work we determine the hyperfine tensors for the ground and excited states on the optical $^2$F$_{7/2}(0) \longleftrightarrow ^2$F$_{5/2}$(0) transition by combining spectral holeburning and optically detected magnetic resonance techniques. The resulting spin Hamiltonians correctly predict the magnetic-field dependence of all observed optical-hyperfine transitions, from zero applied field to the high-field regime where the Zeeman interaction is dominating. Using the optical absorption spectrum we can also determine the order of the hyperfine levels in both states. These results pave the way for realizing solid-state optical and microwave quantum memories based on a $^{171}$Yb$^{3+}$:Y$_2$SiO$_5$ crystal.

quant-ph↗
arXiv2018

Cavity-enhanced spectroscopy of a few-ion ensemble in Eu3+:Y2O3

We report on the coupling of the emission from a single europium-doped nanocrystal to a fiber-based microcavity under cryogenic conditions. As a first step, we study the sample properties and observe a strong correlation between emission lifetime and brightness, as well as a lifetime reduction for nanocrystals embedded in a polymer film. This is explained by differences in the local density of states. We furthermore quantify the scattering loss of a nanocrystal inside the cavity and use this to deduce the crystal size. Finally, by resonantly coupling the cavity to a selected transition, we perform cavity-enhanced spectroscopy to measure the inhomogeneous linewidth, and detect the fluorescence from an ensemble of few ions in the regime of power broadening. We observe an increased fluorescence rate consistent with Purcell enhancement. The results represent an important step towards the efficient readout of single rare-earth ions with excellent optical and spin coherence properties, which is promising for applications in quantum communication and distributed quantum computation.

physics.optics↗
arXiv2018

Efficient optical pumping using hyperfine levels in $^{145}$Nd$^{3+}$:Y$_2$SiO$_5$ and its application to optical storage

Efficient optical pumping is an important tool for state initialization in quantum technologies, such as optical quantum memories. In crystals doped with Kramers rare-earth ions, such as erbium and neodymium, efficient optical pumping is challenging due to the relatively short population lifetimes of the electronic Zeeman levels, of the order of 100 ms at around 4 K. In this article we show that optical pumping of the hyperfine levels in isotopically enriched $^{145}$Nd$^{3+}$:Y$_2$SiO$_5$ crystals is more efficient, owing to the longer population relaxation times of hyperfine levels. By optically cycling the population many times through the excited state a nuclear-spin flip can be forced in the ground-state hyperfine manifold, in which case the population is trapped for several seconds before relaxing back to the pumped hyperfine level. To demonstrate the effectiveness of this approach in applications we perform an atomic frequency comb memory experiment with 33% storage efficiency in $^{145}$Nd$^{3+}$:Y$_2$SiO$_5$, which is on a par with results obtained in non-Kramers ions, e.g. europium and praseodymium, where optical pumping is generally efficient due to the quenched electronic spin. Efficient optical pumping in neodymium-doped crystals is also of interest for spectral filtering in biomedical imaging, as neodymium has an absorption wavelength compatible with tissue imaging. In addition to these applications, our study is of interest for understanding spin dynamics in Kramers ions with nuclear spin.

quant-ph↗
arXiv2018

Simultaneous coherence enhancement of optical and microwave transitions in solid-state electronic spins

Solid-state electronic spins are extensively studied in quantum information science, as their large magnetic moments offer fast operations for computing and communication, and high sensitivity for sensing. However, electronic spins are more sensitive to magnetic noise, but engineering of their spectroscopic properties, e.g. using clock transitions and isotopic engineering, can yield remarkable spin coherence times, as for electronic spins in GaAs, donors in silicon and vacancy centres in diamond. Here we demonstrate simultaneously induced clock transitions for both microwave and optical domains in an isotopically purified $^{171}$Yb$^{3+}$:Y$_2$SiO$_5$ crystal, reaching coherence times of above 100 $μ$s and 1 ms in the optical and microwave domain, respectively. This effect is due to the highly anisotropic hyperfine interaction, which makes each electronic-nuclear state an entangled Bell state. Our results underline the potential of $^{171}$Yb$^{3+}$:Y$_2$SiO$_5$ for quantum processing applications relying on both optical and spin manipulation, such as optical quantum memories, microwave-tooptical quantum transducers, and single spin detection, while they should also be observable in a range of different materials with anisotropic hyperfine interaction.

quant-ph↗
arXiv2018

Characterization of the hyperfine interaction of the excited $^5$D$_0$ state of Eu$^{3+}$:Y$_2$SiO$_5$

We characterize the Europium (Eu$^{3+}$) hyperfine interaction of the excited state ($^5$D$_0$) and determine its effective spin Hamiltonian parameters for the Zeeman and quadrupole tensors. An optical free induction decay method is used to measure all hyperfine splittings under weak external magnetic field (up to 10 mT) for various field orientations. On the basis of the determined Hamiltonian we discuss the possibility to predict optical transition probabilities between hyperfine levels for the $^7$F$_{0} \longleftrightarrow ^5$D$_{0}$ transition. The obtained results provide necessary information to realize an optical quantum memory scheme which utilizes long spin coherence properties of $^{151}$Eu$^{3+}$:Y$_2$SiO$_5$ material under external magnetic fields

quant-ph↗
arXiv2018

Electron Spin Coherences in Rare-Earth Optically Excited States for Microwave to Optical Quantum Transducers

Efficient and reversible optical to microwave coherent transducers are required to enable entanglement transfer between superconducting qubits and light for quantum networks. Rare-earth-doped crystals that possess narrow optical and spin transitions are a promising way to implement these devices. Current approaches use ground-state electron spin transitions that have coherence lifetimes ($T_2$) often limited by spin flip-flop processes and/or spectral diffusion, even at very low temperatures. Here, we investigate spin coherence in an optically excited state of an Er$^{3+}$:Y$_2$SiO$_5$ crystal at temperatures from 1.6 to 3.5 K and under a weak 8.7 mT magnetic field. Spin coherence and population lifetimes of up to 1.6 $μ$s and 1.2 ms, respectively, are measured by 2- and 3-pulse optically-detected spin echo experiments. Analysis of the dephasing processes suggest that ms $T_2$ can be reached at lower temperatures for the excited-state spins, whereas ground-state spin states could be limited to a few $μ$s due to resonant interactions with the other Er$^{3+}$ spins in the lattice (spin diffusion). We propose a quantum transducer scheme with the potential for close to unit efficiency that exploits the specific advantages offered by the spin states of optically excited electronic energy levels.

quant-ph↗
arXiv2017

Coherent spin dynamics of ytterbium ions in yttrium orthosilicate

We investigate the electron and nuclear spin coherence properties of ytterbium ($\mathrm{Yb}^{3+}$) ions with non-zero nuclear spin, within an yttrium orthosilicate (Y$_2$SiO$_5$) crystal, with a view to their potential application in quantum memories or repeaters. We find electron spin-lattice relaxation times are maximised at low magnetic field ($<100$ mT) where $g~\sim6$, reaching 5 s at 2.5 K, while coherence times are maximised when addressing ESR transitions at higher fields where $g\sim0.7$ where a Hahn echo measurement yields $T_2$ up to 73 $μ$s. Dynamical decoupling (XY16) can be used to suppress spectral diffusion and extend the coherence lifetime to over 0.5 ms, close to the limit of instantaneous diffusion. Using Davies electron-nuclear-double-resonance (ENDOR), we performed coherent control of the $^{173}\mathrm{Yb}^{3+}$ nuclear spin and studied its relaxation dynamics. At around 4.5 K we measure a nuclear spin $T_1$ and $T_2$ of 4 and 0.35 ms, respectively, about 4 and 14 times longer than the corresponding times for the electron spin.

quant-ph↗
arXiv2016

Spectral hole lifetimes and spin population relaxation dynamics in neodymium-doped yttrium orthosilicate

We present a detailed study of the lifetime of optical spectral holes due to population storage in Zeeman sublevels of Nd$^{3+}$:Y$_2$SiO$_5$. The lifetime is measured as a function of magnetic field strength and orientation, temperature and Nd$^{3+}$ doping concentration. At the lowest temperature of 3 K we find a general trend where the lifetime is short at low field strengths, then increases to a maximum lifetime at a few hundreds of mT, and then finally decays rapidly for high field strengths. This behaviour can be modelled with a relaxation rate dominated by Nd$^{3+}$-Nd$^{3+}$ cross relaxation at low fields and spin lattice relaxation at high magnetic fields. The maximum lifetime depends strongly on both the field strength and orientation, due to the competition between these processes and their different angular dependencies. The cross relaxation limits the maximum lifetime for concentrations as low as 30 ppm of Nd$^{3+}$ ions. By decreasing the concentration to less than 1 ppm we could completely eliminate the cross relaxation, reaching a lifetime of 3.8 s at 3~K. At higher temperatures the spectral hole lifetime is limited by the magnetic-field independent Raman and Orbach processes. In addition we show that the cross relaxation rate can be strongly reduced by creating spectrally large holes of the order of the optical inhomogeneous broadening. Our results are important for the development and design of new rare-earth-ion doped crystals for quantum information processing and narrow-band spectral filtering for biological tissue imaging.

cond-mat.mtrl-sci↗
arXiv2016

High Resolution Optical Spectroscopy and Magnetic Properties of Yb3+ in Y2SiO5

Rare earth doped crystals are promising systems for quantum information processing. In particular paramagnetic rare earths could be used to build coherent interfaces with optical and microwave photons. In addition, isotopes with non zero nuclear spins could provide long lived states for quantum state storage and processing. Yb3+ is particularly interesting in this respect since it is the only paramagnetic rare earth with a spin 1/2 isotope, which corresponds to the simplest possible level structure. In this paper, we report on the optical and magnetic properties of Yb3+ in the two sites of Y2SiO5, a commonly used crystal for quantum applications. We measured optical inhomogeneous linewidths, peak absorption coefficients, oscillator strengths, excited state lifetimes and fuorescence branching ratios. The Zeeman tensors were also determined in the ground and excited states, as well as the ground state hyperfine tensor for the 171Yb3+ (I = 1=2) isotope. These results suggest that Yb3+:Y2SiO5 is a promising material for applications like solid state optical and microwave quantum memories.

cond-mat.mtrl-sci↗
arXiv2016

High precision measurement of the Dzyaloshinsky-Moriya interaction between two rare-earth ions in a solid

We report on a direct measurement of the pair-wise anti-symmetric exchange interaction, known as the Dzyaloshinsky-Moriya interaction (DMI), in a Nd3+-doped YVO4 crystal. To this end we introduce a broadband electron spin resonance technique coupled with an optical detection scheme which selectively detects only one Nd3+-Nd3+ pair. Using this technique we can fully determine the spin-spin coupling tensor, allowing us to experimentally determine both the strength and direction of the DMI vector. We believe that this ability to fully determine the interaction Hamiltonian is of interest for studying the numerous magnetic phenomena where the DMI interaction is of fundamental importance, including multiferroics. We also detect a singlet-triplet transition within the pair, with a highly suppressed magnetic-field dependence, which suggests that such systems could form singlet-triplet qubits with long coherence times for quantum information applications.

cond-mat.mes-hall↗