| 1. |
- Gutierrez Latorre, Martí, 1993, et al.
(författare)
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Superconducting Microsphere Magnetically Levitated in an Anharmonic Potential with Integrated Magnetic Readout
- 2023
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Ingår i: Physical Review Applied. - 2331-7019. ; 19:5
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Tidskriftsartikel (refereegranskat)abstract
- Magnetically levitated superconducting microparticles offer a promising path to quantum experiments with picogram to microgram objects. In this work, we levitate a 700 ng∼1017amu superconducting microsphere in a magnetic chip trap in which detection is integrated. We measure the center-of-mass motion of the particle using a dc superconducting quantum interference device magnetometer. The trap frequencies are continuously tunable between 30 and 160 Hz and the particle remains stably trapped over days in a dilution-refrigerator environment. We characterize the motional-amplitude-dependent frequency shifts, which arise from trap anharmonicities, namely, Duffing nonlinearities and mode couplings. We explain this nonlinear behavior using finite-element modeling of the chip-based trap potential. This work may constitute a first step toward quantum experiments and ultrasensitive inertial sensors with magnetically levitated superconducting microparticles.
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| 2. |
- Gutierrez, Martí, 1993, et al.
(författare)
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A chip-based superconducting magnetic trap for levitating superconducting microparticles
- 2022
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Ingår i: IEEE Transactions on Applied Superconductivity. - 1558-2515 .- 1051-8223. ; 32:4
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Tidskriftsartikel (refereegranskat)abstract
- Magnetically-levitated superconducting microparticles have been recently proposed as a promising platform for performing quantum experiments with particles in the picogram regime. Here, we demonstrate the superconducting technology to achieve chip-based magnetic levitation of superconducting microparticles. We simulate and fabricate a chip-based magnetic trap capable of levitating superconducting particles with diameters from 0.5m to 200m. The trap consists of two stacked silicon chips, each patterned with a planar multi-winding superconducting coil made of niobium. The two coils generate a magnetic field resembling a quadrupole near the trap center, in which we demonstrate trapping of a spherical 50m diameter SnPb microparticle at temperatures of 4K and 40mK.
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| 3. |
- Higgins, Gerard, 1989-
(författare)
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A single trapped Rydberg ion
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Systems of trapped ions and systems of ultracold Rydberg atoms are used at the forefront of quantum physics research and they make strong contenders as platforms for quantum technologies. Trapped Rydberg ions are a new hybrid technology envisaged to have both the exquisite control of trapped ion systems and the strong interactions of Rydberg atoms. In this work a single trapped Rydberg ion is experimentally investigated. A trapped 88Sr+ ion is excited to Rydberg states using two ultraviolet lasers. Effects of the strong trapping electric fields on the sensitive Rydberg ion are studied. After mitigating unwanted trap effects, the ion is coherently excited to Rydberg states and a quantum gate is demonstrated. This thesis lays much of the experimental groundwork for research using this novel system.
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| 4. |
- Higgins, Gerard, 1989, et al.
(författare)
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Maglev for dark matter: Dark-photon and axion dark matter sensing with levitated superconductors
- 2024
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Ingår i: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 2470-0010 .- 2470-0029. ; 109:5
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Tidskriftsartikel (refereegranskat)abstract
- Ultraprecise mechanical sensors offer an exciting avenue for testing new physics. While many of these sensors are tailored to detect inertial forces, magnetically levitated (Maglev) systems are particularly interesting, in that they are also sensitive to electromagnetic forces. In this work, we propose the use of magnetically levitated superconductors to detect dark-photon and axion dark matter through their couplings to electromagnetism. Several existing laboratory experiments search for these dark-matter candidates at high frequencies, but few are sensitive to frequencies below 1 kHz (corresponding to dark-matter masses mDM≲10-12 eV). As a mechanical resonator, magnetically levitated superconductors are sensitive to lower frequencies, and so can probe parameter space currently unexplored by laboratory experiments. Dark-photon and axion dark matter can source an oscillating magnetic field that drives the motion of a magnetically levitated superconductor. This motion is resonantly enhanced when the dark matter Compton frequency matches the levitated superconductor's trapping frequency. We outline the necessary modifications to make magnetically levitated superconductors sensitive to dark matter, including specifications for both broadband and resonant schemes. We show that in the Hz≲fDM≲kHz frequency range our technique can achieve the leading sensitivity among laboratory probes of both dark-photon and axion dark matter.
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| 5. |
- Higgins, Gerard, 1989, et al.
(författare)
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Micromotion minimization using Ramsey interferometry
- 2021
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 23:12
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Tidskriftsartikel (refereegranskat)abstract
- We minimize the stray electric field in a linear Paul trap quickly and accurately, by applying interferometry pulse sequences to a trapped ion optical qubit. The interferometry sequences are sensitive to the change of ion equilibrium position when the trap stiffness is changed, and we use this to determine the stray electric field. The simplest pulse sequence is a two-pulse Ramsey sequence, and longer sequences with multiple pulses offer a higher precision. The methods allow the stray field strength to be minimized beyond state-of-the-art levels. Using a sequence of nine pulses we reduce the 2D stray field strength to (10.5 +/- 0.8) mV m(-1) in 11 s measurement time. The pulse sequences are easy to implement and automate, and they are robust against laser detuning and pulse area errors. We use interferometry sequences with different lengths and precisions to measure the stray field with an uncertainty below the standard quantum limit. This marks a real-world case in which quantum metrology offers a significant enhancement. Also, we minimize micromotion in 2D using a single probe laser, by using an interferometry method together with the resolved sideband method; this is useful for experiments with restricted optical access. Furthermore, a technique presented in this work is related to quantum protocols for synchronizing clocks; we demonstrate these protocols here.
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| 6. |
- Hofer, J., et al.
(författare)
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High- Q Magnetic Levitation and Control of Superconducting Microspheres at Millikelvin Temperatures
- 2023
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 131:4
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Tidskriftsartikel (refereegranskat)abstract
- We report the levitation of a superconducting lead-tin sphere with 100 μm diameter (corresponding to a mass of 5.6 μg) in a static magnetic trap formed by two coils in an anti-Helmholtz configuration, with adjustable resonance frequencies up to 240 Hz. The center-of-mass motion of the sphere is monitored magnetically using a dc superconducting quantum interference device as well as optically and exhibits quality factors of up to 2.6×107. We also demonstrate 3D magnetic feedback control of the motion of the sphere. The setup is housed in a dilution refrigerator operating at 15 mK. By implementing a cryogenic vibration isolation system, we can attenuate environmental vibrations at 200 Hz by approximately 7 orders of magnitude. The combination of low temperature, large mass, and high quality factor provides a promising platform for testing quantum physics in previously unexplored regimes with high mass and long coherence times.
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| 7. |
- Lourenço, José A. S., et al.
(författare)
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Non-Hermitian dynamics and PT-symmetry breaking in interacting mesoscopic Rydberg platforms
- 2022
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 106:2
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Tidskriftsartikel (refereegranskat)abstract
- We simulate the dissipative dynamics of a mesoscopic system of long-range interacting particles which can be mapped into non-Hermitian spin models with a PT symmetry. We find rich PT phase diagrams with PT-symmetric and PT-broken phases. The dynamical regimes can be further enriched by modulating tunable parameters of the system. We outline how the PT symmetries of such systems may be probed by studying their dynamics. We note that systems of Rydberg atoms and systems of Rydberg ions with strong dipolar interactions are particularly well suited for such studies. We present a viable proposal for implementing non-Hermitian physics with PT symmetry in Rydberg systems. We show that for realistic parameters, long-range interactions allow the emergence of new PT-symmetric regions, generating new PT phase transitions. In addition, such PT-symmetry phase transitions are found by changing the configurations of the Rydberg atoms. We propose a post selection scheme on an ensemble of Rydberg ions described by an effective three-level system. Detecting the population dynamics, the system shows an oscillatory behavior in the PT-unbroken phase and a stationary population for long times in the PT-broken phase.
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| 8. |
- Mallweger, Marion, et al.
(författare)
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Single-Shot Measurements of Phonon Number States Using the Autler-Townes Effect
- 2023
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 131:22
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Tidskriftsartikel (refereegranskat)abstract
- We present a single-shot method to measure motional states in the number basis. The technique can be applied to systems with at least three nondegenerate energy levels which can be coupled to a linear quantum harmonic oscillator. The method relies on probing an Autler-Townes splitting that arises when a phonon-number changing transition is strongly coupled. We demonstrate the method using a single trapped ion and show that it may be used in a nondemolition fashion to prepare phonon number states. We also show how the Autler-Townes splitting can be used to measure phonon number distributions.
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| 9. |
- Mallweger, Marion, 1997-, et al.
(författare)
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Single-Shot Measurements of Phonon Number States Using the Autler-Townes Effect
- 2023
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 131:22
-
Tidskriftsartikel (refereegranskat)abstract
- We present a single-shot method to measure motional states in the number basis. The technique can be applied to systems with at least three nondegenerate energy levels which can be coupled to a linear quantum harmonic oscillator. The method relies on probing an Autler-Townes splitting that arises when a phonon-number changing transition is strongly coupled. We demonstrate the method using a single trapped ion and show that it may be used in a nondemolition fashion to prepare phonon number states. We also show how the Autler-Townes splitting can be used to measure phonon number distributions.
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| 10. |
- Oliveira, Murilo H., et al.
(författare)
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Steady-state entanglement generation for nondegenerate qubits
- 2023
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 107:2
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Tidskriftsartikel (refereegranskat)abstract
- We propose a scheme to dissipatively produce steady-state entanglement in a two-qubit system, via an interaction with a bosonic mode. The system is driven into a stationary entangled state, while we compensate the mode dissipation by injecting energy via a coherent pump field. We also present a scheme which allows us to adiabatically transfer all the population to the desired entangled state. The dynamics leading to the entangled state in these schemes can be understood in analogy with electromagnetically induced transparency and stimulated Raman adiabatic passage, respectively.
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