Bulletin of the American Physical Society
APS March Meeting 2023
Las Vegas, Nevada (March 510)
Virtual (March 2022); Time Zone: Pacific Time
Session Q74: Semiconducting Qubits IFocus

Hide Abstracts 
Sponsoring Units: DQI Chair: Romain Maurand, CEA Grenoble Room: Room 403/404 
Wednesday, March 8, 2023 3:00PM  3:36PM 
Q74.00001: The emergence of the strong dispersive regime of circuit quantum electrodynamics with spins Invited Speaker: Patrick HarveyCollard Circuit quantum electrodynamics with spins, or spincircuit QED for short, is perceived as a platform for scaling up semiconductor spin qubits by enabling longrange interaction between spin qubits and dispersive spin readout. 
Wednesday, March 8, 2023 3:36PM  3:48PM 
Q74.00002: Towards an ExchangeOnly Compatible SpinPhoton Interface in Si/SiGe Nathan S Holman Coherent coupling of spin qubits to microwave photons has in recent years been demonstrated in Si/SiGe teasing the possibility of longrange twoqubit gates [1, 2]. In most demonstrations, spinphoton coupling is engineered by placement of micromagnets on top of the quantum dot gate stack creating an alwayson chargespin hybridization. Gradient magnetic fields, however, are fundamentally incompatible with exchangeonly qubit operation as they induce state leakage out of the decoherencefree subsystem. An alternative approach that is compatible with exchangeonly operation is to use large simultaneous exchange pulses to create a biasdependent electric dipole moment in the “XRX” regime [3]. In this talk we discuss the integration and characterization of Single Layer Etch Defined Gate Electrode (SLEDGE) devices, which rely on vias to separate frontend from backend interconnects, with superconducting microwave resonators using flipchip bonding [4]. 
Wednesday, March 8, 2023 3:48PM  4:00PM 
Q74.00003: Onchip filters for highimpedance superconducting resonators in the hybrid cQED device architecture Xuanzi Zhang, Jason R Petta In hybrid quantum dot (QD)cQED systems, superconducting microwave resonators are used as mediators for nonlocal qubit interactions. Highimpedance resonators are desirable, as the increased impedance enhances the chargephoton coupling rate and moves the system deeper into the strong spinphoton coupling regime. However, higher impedance can cause significant microwave leakage through the dc bias lines used to form the QDs. Onchip LC filters on each gate line have been shown to improve the quality factor of the highZ resonator [1,2]. Last year, we reported direct current resistivity measurements and microwave investigations of niobium nitride (NbN) films of different thicknesses. We measured a large kinetic inductance of LK ∼ 41.2 pH/sq and sheet resistance of R_{s} ~ 274 Ohm/sq for 15 nm NbN thin films. I will summarize our previous findings and introduce the next step to incorporate lowpass LC filters into our current cavity design. We measured the transmission through the filters to evaluate the attenuation of different filter designs. Implementing the LC filters on the QDcQED chip will suppress microwave leakage through the dc bias lines, resulting in a significant increase in the cavity quality factor. 
Wednesday, March 8, 2023 4:00PM  4:12PM 
Q74.00004: Longdistance entangling gates in threequbit quantum dot spin systems mediated by microwave photons Nooshin M. Estakhri, Ada Warren, Edwin Barnes, Sophia Economou Attaining quantum dot (QD)based processors with large number of qubits remains as a major experimental challenge. Recently, longdistance entangling gates between two electronic spins in double QDs mediated by microwave resonators have been developed. While this serves as an important initial step, scaling the systems to qubit numbers larger than two is crucial. We focus on threequbit—resonator system, a twoelectron triple QD coupled to a singleelectron double QD via the resonator. We derive an effective Hamiltonian for this system and build protocols for highfidelity entangling gates. This study paves the way for modular quantum computing using QD arrays with manageable number of qubits and resonators as quantum information busses. 
Wednesday, March 8, 2023 4:12PM  4:24PM 
Q74.00005: Strong coupling between a microwave photon and a singlettriplet qubit Jann Hinnerk Ungerer, Alessia Pally, Artem Kononov, Sebastian Lehmann, Joost Ridderbos, Claes Thelander, Kimberly A Dick, Ville F Maisi, Pasquale Scarlino, Andreas Baumgartner, Christian Schonenberger Spin qubits in semiconuctors are promising contenders for realizing scalable quantum computers because of their small footprint, long coherence times and fast gate operations. However, entangling gates between spin qubits are short range, limiting the scaleup towards larger quantum processors. 
Wednesday, March 8, 2023 4:24PM  4:36PM 
Q74.00006: Spin qubits in photoncoupled microwave cavites Nancy P Sandler, Samuel T Johnson Electron spin qubits in microwave cavities represent a promising foundation for developing quantum computing hardware. Electron spin states have high coherence times compared to gate interaction time scales, and photon coupling allows for longdistance interaction between qubits. The strong spinphoton coupling regime can be realized via the dipole interaction, as Petta et al. [1] demonstrated by placing an electron in a double quantum dot (DQD) with a magnetic field gradient inside a microwave cavity. These studies later included two DQDs inside the cavity to demonstrate longrange spinspin interactions [2]. Input/output theory describes the system's behavior when driven by an external field and determine the internal qubits states from the transmission amplitude of the output field [3]. Our studies showed that additional qubits inside the cavity render lower transmission amplitudes. As an alternative setup, we analyze results from a model of a double DQD qubit system consisting of two cavities, each containing one qubit, coupled via a photonic waveguide that allows for single photon exchange. In analogy with previous works, we utilize input/output theory to obtain transmission amplitudes and discuss the various regimes determined by tuning different parameters. 
Wednesday, March 8, 2023 4:36PM  4:48PM 
Q74.00007: Fast and highfidelity dispersive readout of a spin qubit via squeezing Chonfai Kam Within the framework of inputoutput theory, we analyze the dispersive readout of a single spin in a semiconductor double quantum dot coupled to a microwave resonator. We demonstrate fast and highfidelity readout of semiconductor spin qubits by using squeezed coherent states and nonlinear resonators. We find that for fixed dispersive coupling strength $chi_s$ and leakage rate $kappa$, the presence of squeezing can enhance the signaltonoise ratio as well as the fidelity of the qubitstate readout, whereas the introduction of nonlinearity into the resonator (e.g., via a SQUID) can substantially speed up the optimal readout time. With current technology ($kappaapprox 2pi imes 3.0:mbox{MHz}$, $chi_sapprox 0.15kappa$), using a squeezed coherent state with $50$ photons and a squeezing parameter $rapprox 3.5$, a readout fidelity $Fapprox 90\%$ is achievable within a readout time $tapprox 200:mbox{ns}$, which is one order of magnitude faster than the optimal readout time ($approx 2:mu$s) without squeezing. Under the same condition, $Fapprox 95\%$ is achievable within a readout time $tapprox 100:mbox{ns}$ with a squeezing parameter $rapprox 6$ and a nonlinear strength $lambdaapprox 0.7kappa$. 
Wednesday, March 8, 2023 4:48PM  5:00PM 
Q74.00008: Interplay of Pauli Blockade with ElectronPhoton Coupling in Quantum Dots Florian Ginzel, Guido Burkard Both quantum transport measurements in the Pauli blockade regime and microwave cavity transmission measurements are important tools for spinqubit readout and characterization. In our work [1] we theoretically investigate how a double quantum dot in a transport setup interacts with a coupled microwave resonator while the current through the DQD is rectified by Pauli blockade. We show that the output field of the resonator can be used to infer the leakage current and thus obtain insight into the blockade mechanisms without additional components such as charge or current sensors for each dot. In the case double quantum dot realized in silicon, we show how the valley quasidegeneracy can impose limitations on this scheme. We also demonstrate that a large number of unknown double quantum dot parameters including (but not limited to) the valley splitting can be estimated from the resonator response simultaneous to a transport experiment, providing more detailed knowledge about the microscopic environment of the dots. Furthermore, we describe and quantify a backaction of the resonator photons on the steady state leakage current. 
Wednesday, March 8, 2023 5:00PM  5:12PM 
Q74.00009: Longitudinal coupling to hole spin qubits demonstrated in a silicon fin fieldeffect transistor Simon Geyer, Stefano Bosco, Leon C Camenzind, Rafael S Eggli, Taras Patlatiuk, Daniel Loss, Richard J Warburton, Dominik M Zumbuhl, Andreas V Kuhlmann Quantum computers promise exponential speedup for certain problems. Silicon quantum dot holes spin qubits are prime candidates for scalable quantum computing owing to their small footprint and compatibility with current semiconductor foundry fabrication techniques. The devices used here are silicon fin fieldeffect transistors (FinFETs) [1] which allow for spin qubit operation above 4K [2]. 
Wednesday, March 8, 2023 5:12PM  5:24PM 
Q74.00010: Twotone electrical drive of spin qubits J. Carlos Egues, Stefano Bosco, Daniel Loss Longitudinal coupling of spin qubits to resonators has recently been demonstrated [1]. Theoretically, it had already been proposed as a resource to implement fast twoqubit gates in Si and Ge hole quantum dots [2]. Motivated by recent experiments on Si spin qubits in fin fieldeffect transistors [3] demonstrating spin qubit operations up to 4 K [4], here we theoretically investigate bimodal electrical microwave driving (transverse and longitudinal) of single spin qubits. The interplay of these drives at differing frequencies gives rise to a wealth of interesting physical phenomena. For instance, the longitudinal modulation induces a gap in the Floquet spectrum of the system, thus making the qubits more robust. We also discuss our findings in light of recent data [5]. Our theoretical description is general and could be applied to both electron and hole quantum dot qubits. 
Wednesday, March 8, 2023 5:24PM  5:36PM 
Q74.00011: Longitudinal coupling used for resonator readout of quantum dot qubits Benjamin Harpt, Joelle J Corrigan, Nathan S Holman, Piotr Marciniec, Danna Rosenberg, DonnaRuth W Yost, Rabindra Das, William D Oliver, Robert McDermott, Mark Friesen, Mark A Eriksson Superconducting resonators coupled to quantum dot qubits are expected to form key components in scalable quantum computing architectures [1]. Longitudinal coupling mechanisms in these systems can enable quantumnondemolition readout even when the qubit and resonator frequencies are far apart [2,3]. This type of coupling has only recently been measured in quantum dot qubit devices [4], and its full utility remains undemonstrated. Here, we show resonator readout of a quantum dot hybrid qubit using dynamic longitudinal coupling, which is turned on by applying an ac modulation to the qubit. Good visibility is achieved at qubitcavity detuning over 10 GHz. This allows measurement of qubit energy splittings, which are confirmed using reservoir tunneling spectroscopy. We assess the readout signaltonoise ratio and discuss how to maximize its value for qubit operation by tuning the longitudinal coupling strength. Tunability and frequency flexibility are appealing features of dynamic longitudinal coupling, and our work demonstrates its potential as a powerful new technique for semiconductor qubit readout. 
Wednesday, March 8, 2023 5:36PM  5:48PM 
Q74.00012: Remote entanglement by measurement of spin qubits via longitudinal (curvature) couplings to a superconducting resonator Rusko Ruskov, Charles Tahan Remote entanglement of spin qubits is an important resource for quantum communications, and quantum simulations. Based on our previous proposals [1,2] we study the feasibility of remote entanglement of spin qubits via joint continuous measurement by a superconducting resonator using longitudinal (curvature) couplings. As examples, we consider (i) double quantum dot (DQD) SingletTriplet qubits at the charge degeneracy point and (ii) DQD charge qubits with magnetic field gradient, both relevant to current experiments. The effects of charge dephasing and T1 (Purcell) relaxation as well as effects of measurement asymmetry and local qubit rotations on the entanglement fidelity are considered. 
Wednesday, March 8, 2023 5:48PM  6:00PM 
Q74.00013: Electricdipole spin resonance of a flopping mode acceptordot hybrid FelixEkkehard von Horstig Strong spinorbit coupling for holes in silicon gives rise to location and field orientation dependant gfactors. SOC is further enhanced for socalled flopping mode qubits where a single hole is electrically driven between two quantum dots with different gfactors, which converts the electrical drive into an effective magnetic drive in the reference frame of the hole allowing for efficient electric dipole spin resonance (EDSR) to be driven. 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2023 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
1 Research Road, Ridge, NY 119612701
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700