The quest towards precise measurement and control of quantum mechanical systems is behind many if not most of the advances in mesoscopic physics in the recent years. This thesis follows that tradition, and describes the first realization of a hybrid circuit integrating electrons on helium (EonHe) with the circuit quantum electrodynamics (cQED) architecture. In this hybrid architecture, the quantized lateral motion of the electrons strongly couples with the transverse electric field inside a high-Q superconducting resonator, enabling sensitive detection and manipulation of the electron's in-plane motion degree of freedom. Such architecture also provide a plausible road map towards using the spin degrees of freedom of the electrons as a quantum memory. Our hope is to establish a novel model system for quantum control and manipulation, where the uncanny similarity between the electron hamiltonian and the strong coulomb interactions could give rise to unparallelly rich quantum phenomena. In our first experiment towards this goal, we demonstrate strong dispersive coupling between $\sim 10^5$ electrons and a superconducting co-planar waveguide resonator. The effort of the second experiment focuses on bringing down this number to just a few electrons in an isolated trap. The CPW resonator was replaced by a quarter-wavelength strip-line resonator with one side terminated by a short (``the tuning fork"). This design changes the microwave mode that is visible to the electron dipole interaction, improves the coupling strength, and opens up the geometry for more sophisticated DC controls isolating an individual electron. The third experiment implements such DC control scheme, and manages to trap just a single electron in a small trap. This small electron trap is defined by multiple DC electrodes near the open-end of the tuning fork. The overall circuit design resembles those seen in the quantum dot community. Much effort was spent on hitting the tight space between the dispersive constraints of the cQED measurement scheme and the increasing complication of the sample. Single or few electron spectra are measured, and we provided an upper estimate on the acoustically broadened electron line-width, together with design changes that reduce the line-width of the electron states.The quest towards precise measurement and control of quantum mechanical systems is behind many if not most of the advances in mesoscopic physics in the recent years. This thesis follows that tradition, and describes the first realization of a hybrid circuit integrating electrons on helium (EonHe) with the circuit quantum electrodynamics (cQED) architecture. In this hybrid architecture, the quantized lateral motion of the electrons strongly couples with the transverse electric field inside a high-Q superconducting resonator, enabling sensitive detection and manipulation of the electron's in-plane motion degree of freedom. Such architecture also provide a plausible road map towards using the spin degrees of freedom of the electrons as a quantum memory. Our hope is to establish a novel model system for quantum control and manipulation, where the uncanny similarity between the electron hamiltonian and the strong coulomb interactions could give rise to unparallelly rich quantum phenomena. In our first experiment towards this goal, we demonstrate strong dispersive coupling between $\sim 10^5$ electrons and a superconducting co-planar waveguide resonator. The effort of the second experiment focuses on bringing down this number to just a few electrons in an isolated trap. The CPW resonator was replaced by a quarter-wavelength strip-line resonator with one side terminated by a short (``the tuning fork"). This design changes the microwave mode that is visible to the electron dipole interaction, improves the coupling strength, and opens up the geometry for more sophisticated DC controls isolating an individual electron. The third experiment implements such DC control scheme, and manages to trap just a single electron in a small trap. This small electron trap is defined by multiple DC electrodes near the open-end of the tuning fork. The overall circuit design resembles those seen in the quantum dot community. Much effort was spent on hitting the tight space between the dispersive constraints of the cQED measurement scheme and the increasing complication of the sample. Single or few electron spectra are measured, and we provided an upper estimate on the acoustically broadened electron line-width, together with design changes that reduce the line-width of the electron states.

Mar 1, 20200 citations

Fast Tunable High- Q -Factor Superconducting Microwave Resonators

Sumedh Mahashabde, Ernst Otto, Domenico Montemurro +3 more

We present fast tunable superconducting microwave resonators fabricated from planar $\mathrm{Nb}\mathrm{N}$ on a sapphire substrate. The $3\ensuremath{\lambda}/4$ wavelength resonators are tuning fork shaped and tuned by passing a dc current that controls the kinetic inductance of the tuning fork prongs. The $\ensuremath{\lambda}/4$ section from the open end operates as an integrated impedance converter that creates a nearly perfect short for microwave currents at the dc terminal coupling points, thus preventing microwave energy leakage through the dc lines. We measure an internal quality factor ${Q}_{\mathrm{int}}>{10}^{5}$ over the entire tuning range. We demonstrate a tuning range of greater than $3\mathrm{%}$ and tuning response times as short as 20 ns for the maximum achievable detuning. Because of the quasifractal design, the resonators are resilient to magnetic fields of up to 0.5 T.We present fast tunable superconducting microwave resonators fabricated from planar $\mathrm{Nb}\mathrm{N}$ on a sapphire substrate. The $3\ensuremath{\lambda}/4$ wavelength resonators are tuning fork shaped and tuned by passing a dc current that controls the kinetic inductance of the tuning fork prongs. The $\ensuremath{\lambda}/4$ section from the open end operates as an integrated impedance converter that creates a nearly perfect short for microwave currents at the dc terminal coupling points, thus preventing microwave energy leakage through the dc lines. We measure an internal quality factor ${Q}_{\mathrm{int}}>{10}^{5}$ over the entire tuning range. We demonstrate a tuning range of greater than $3\mathrm{%}$ and tuning response times as short as 20 ns for the maximum achievable detuning. Because of the quasifractal design, the resonators are resilient to magnetic fields of up to 0.5 T.

arXiv:2003.11068Physical Review AppliedOct 21, 202063 citations

Nanoscale real-time detection of quantum vortices at millikelvin temperatures

A. Guthrie, S. Kafanov, M. T. Noble +6 more

Abstract Since we still lack a theory of classical turbulence, attention has focused on the conceptually simpler turbulence in quantum fluids. Reaching a better understanding of the quantum case may provide additional insight into the classical counterpart. That said, we have hitherto lacked detectors capable of the real-time, non-invasive probing of the wide range of length scales involved in quantum turbulence. Here we demonstrate the real-time detection of quantum vortices by a nanoscale resonant beam in superfluid 4 He at 10 mK. Essentially, we trap a single vortex along the length of a nanobeam and observe the transitions as a vortex is either trapped or released, detected through the shift in the beam resonant frequency. By exciting a tuning fork, we control the ambient vortex density and follow its influence on the vortex capture and release rates demonstrating that these devices are capable of probing turbulence on the micron scale.Abstract Since we still lack a theory of classical turbulence, attention has focused on the conceptually simpler turbulence in quantum fluids. Reaching a better understanding of the quantum case may provide additional insight into the classical counterpart. That said, we have hitherto lacked detectors capable of the real-time, non-invasive probing of the wide range of length scales involved in quantum turbulence. Here we demonstrate the real-time detection of quantum vortices by a nanoscale resonant beam in superfluid 4 He at 10 mK. Essentially, we trap a single vortex along the length of a nanobeam and observe the transitions as a vortex is either trapped or released, detected through the shift in the beam resonant frequency. By exciting a tuning fork, we control the ambient vortex density and follow its influence on the vortex capture and release rates demonstrating that these devices are capable of probing turbulence on the micron scale.

arXiv:2007.04482Nature CommunicationsMay 11, 202120 citations

Superconducting micro-resonators for electron spin resonance - the good, the bad, and the future

Yaron Artzi, Yakir Ishay, Marco Fanciulli +2 more

arXiv:2106.04163Journal of Magnetic ResonanceNov 2, 202117 citations

\sim 10^5

electrons and a superconducting co-planar waveguide resonator. The effort of the second experiment focuses on bringing down this number to just a few electrons in an isolated trap. The CPW resonator was replaced by a quarter-wavelength strip-line resonator with one side terminated by a short (``the tuning fork"). This design changes the microwave mode that is visible to the electron dipole interaction, improves the coupling strength, and opens up the geometry for more sophisticated DC controls isolating an individual electron. The third experiment implements such DC control scheme, and manages to trap just a single electron in a small trap. This small electron trap is defined by multiple DC electrodes near the open-end of the tuning fork. The overall circuit design resembles those seen in the quantum dot community. Much effort was spent on hitting the tight space between the dispersive constraints of the cQED measurement scheme and the increasing complication of the sample. Single or few electron spectra are measured, and we provided an upper estimate on the acoustically broadened electron line-width, together with design changes that reduce the line-width of the electron states.

We present fast tunable superconducting microwave resonators fabricated from planar

\mathrm{Nb}\mathrm{N}

on a sapphire substrate. The $3\ensuremath{\lambda}/4$ wavelength resonators are tuning fork shaped and tuned by passing a dc current that controls the kinetic inductance of the tuning fork prongs. The $\ensuremath{\lambda}/4$ section from the open end operates as an integrated impedance converter that creates a nearly perfect short for microwave currents at the dc terminal coupling points, thus preventing microwave energy leakage through the dc lines. We measure an internal quality factor

{Q}_{\mathrm{int}}>{10}^{5}

over the entire tuning range. We demonstrate a tuning range of greater than $3\mathrm{%}$ and tuning response times as short as 20 ns for the maximum achievable detuning. Because of the quasifractal design, the resonators are resilient to magnetic fields of up to 0.5 T.