Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session N72: Semiconductor Qubits: Spin Qubit Measurement II |
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Sponsoring Units: DQI Chair: Sophie Hermans, California Institute of Technology Room: Room 406 |
Wednesday, March 8, 2023 11:30AM - 11:42AM Author not Attending |
N72.00001: Radio Frequency Reflectometry with Impedance Matching on Si:P Monolayer Devices Joseph B Fox, Fan Fei, Ranjit Kashid, Pradeep N Namboodiri, Jonathan Wyrick, Joshua Pomeroy, Richard M Silver, Neil Zimmerman Si:P monolayer quantum devices fabricated using STM based hydrogen lithography are a strong candidate for spin-based quantum computing. Scaling these devices to larger numbers of spin-based donor qubits is impeded by the amount of physical space required for the readout sensors while maintaining high bandwidth measurements. Radio frequency reflectometry addresses these issues by minimizing the physical footprint of the sensor and potentially reduces the sensitivity to noise as the measurement can operate at a higher frequency than DC readout. This presentation will discuss our progress in developing reflectometry that is capable of single shot-readout. We focus on ohmic and capacitive reflectometry, as well as reflectometry on a single lead quantum dot. We are evaluating improved impedance matching for improved signal to noise and will describe the effect on the measurement sensitivity caused by the impedance matching and/or replacing the inductor to be in parallel with the device, rather than in series. |
Wednesday, March 8, 2023 11:42AM - 11:54AM |
N72.00002: Hyperabrupt SrTiO3 Varactors for High-Sensitivity Reflectometry of Quantum Dots Rafael S Eggli, Taras Patlatiuk, Simon Svab, Dominique Trüssel, Simon Geyer, Miguel J Carballido, Erik P. A. M. Bakkers, Richard J Warburton, Andreas V Kuhlmann, Dominik M Zumbuhl The highest-sensitivity readout of spin qubits is typically achieved using radio-frequency (RF) reflectometry techniques. Such methods include RF-single electron transistors (RF-SETs) and gate-dispersive charge sensing. The characteristic impedance of standard RF equipment is 50 W, whereas typical quantum devices impedances are on the order of the quantum resistance h/e2 » 25.8 kW or higher in the case of gate-sensors. Off-chip tank circuits are used to overcome this mismatch but lack in-situ tunability to compensate for temperature-dependencies and device-to device variability. Earlier work [1] has shown that commercial GaAs varactor diodes can be used to in-situ tune the tank circuit to perfect matching, improving sensitivity and measurement speed. However, such voltage-tunable capacitors freeze out at temperatures below 1K and show a significant dependence on magnetic fields. Using quantum paraelectric materials like Strontium Titanate (STO) alleviates these problems [2], but provides only limited tunability compared to GaAs. Here, we report on the characterization of Strontium Titanate (STO) ring-varactors which robustly reach hyperabrupt capacitance tunability. We use those devices to gate-dispersively measure hole quantum dots in GeSi core-shell nanowires and fin-field effect transistors, both promising platforms for spin qubits [3,4]. |
Wednesday, March 8, 2023 11:54AM - 12:06PM Author not Attending |
N72.00003: Design and optimization of a cryogenic CMOS capacitance bridge for readout of silicon spin qubits Ryan H Foote, Ioanna Kriekouki, Claude Rohrbacher, Alexandre Bédard-Vallée, Philippe Galy, Dan Deptuck, Gayathri Singh, Nicolas Roy, Michel Pioro-Ladrière, Jean-François Pratte Despite recent success in the field of quantum information, a clear path to a scalable quantum computing architecture has yet to be found. As the number of high-fidelity qubits in a device increases, so too does the amount of control electrodes and readout structures, rapidly leading to significant connectivity issues. |
Wednesday, March 8, 2023 12:06PM - 12:18PM |
N72.00004: Broadband parametric amplification for multiplexed SiMOS spin qubit readout Victor Elhomsy, David J Niegemann, Luca Planat, Emmanuel Chanrion, Martin Nurizzo, Baptiste Jadot, Vivien Thiney, Renan Lethiecq, Bernhard Klemt, Matthieu C Dartiailh, Pierre A Mortemousque, Benoit Bertrand, Heimanu Niebojewski, Maud Vinet, Nicolas Roch, Tristan Meunier, Matias Urdampilleta Electron spins in semiconductor quantum dots hold great promise as building blocks of quantum processors [1]. Trapping them in SiMOS transistor-like devices eases future industrial scale fabrication [2]. In this prospect, readout schemes must enable to distinguish between the two qubit states with a fidelity above error correction thresholds, while minimizing the sensor footprint. [1] Loss, D., & DiVincenzo, D. P. (1998). Quantum computation with quantum dots. Physical Review A, 57(1), 120. [2] Maurand, R., Jehl, X., Kotekar-Patil, D., Corna, A., Bohuslavskyi, H., Laviéville, R., ... & De Franceschi, S. (2016). A CMOS silicon spin qubit. Nature communications, 7(1), 1-6. [3] Vigneau, F., Fedele, F., Chatterjee, A., Reilly, D., Kuemmeth, F., Gonzalez-Zalba, F., ... & Ares, N. (2022). Probing quantum devices with radio-frequency reflectometry. arXiv preprint arXiv:2202.10516. [4] Planat, L., Ranadive, A., Dassonneville, R., Martínez, J. P., Léger, S., Naud, C., ... & Roch, N. (2020). Photonic-crystal Josephson traveling-wave parametric amplifier. Physical Review X, 10(2), 021021. |
Wednesday, March 8, 2023 12:18PM - 12:30PM |
N72.00005: Dispersive charge sensing of quantum dots in Ge/Si core/shell nanowires Simon Svab, Miguel J Carballido, Rafael S Eggli, Pierre Chevalier Kwon, Erik P. A. M. Bakkers, Taras Patlatiuk, Dominik M Zumbuhl Holes in Germanium/Silicon core/shell nanowires are a powerful platform to study and optimize the properties of spin qubits. This is a consequence of the strong, gate-tunable direct Rashba spin-orbit interaction, which arises from the strong 1D confinement in the nanowire. In turn, this enables toggling a spin qubit between an ultrafast control mode with Rabi frequency above 400 MHz and an idling mode with weaker SOI and longer coherence times (Froning et al. Nat. Nano. 16, 308-312 (2021)). So far, experiments in this system have been done in DC transport, making it hard to measure more than two quantum dots in series and preventing single-shot readout. |
Wednesday, March 8, 2023 12:30PM - 12:42PM |
N72.00006: Coherent manipulation of the Si/SiGe quantum dot hybrid qubit using single-shot latched readout Sanghyeok Park, Jared Benson, Joelle J Corrigan, John P Dodson, Sue N Coppersmith, Mark Friesen, Mark A Eriksson We present single-shot measurements and demonstrate coherent Larmor oscillations of a quantum dot hybrid qubit. Single-shot readout is performed through a single reservoir coupled to a 5-electron double dot in the (4,1)-(3,2) charge configuration. Latching onto the (4,2) charge state is achieved by simultaneously pulsing the gate voltages on barrier and plunger gates, thereby enabling dynamic control of the tunnel rates. We further show that similar pulses on the same gates can speed up qubit initialization by a factor of 15, greatly increasing experimental throughput. We demonstrate that crosstalk between the barrier gates and the quantum dots is only significant for adjacent dots, so that a simple correction scheme is sufficient to fully cancel out the crosstalk. Finally, we discuss the application of our latching scheme to any qubit whose spin states can be adiabatically transformed to charge states of a double quantum dot, including singlet-triplet qubits, exchange-only qubits, and single-spin qubits in parity readout mode. |
Wednesday, March 8, 2023 12:42PM - 12:54PM |
N72.00007: The Effect of Device Drift on Elzerman Readout Fidelity Tommy O Boykin II, Michael D Stewart High-fidelity, single-shot readout of electron spins is needed for fault-tolerant quantum computation. High-fidelity has been achieved using the common method known as Elzerman readout. However, Elzerman readout has the requirement of very high signal-to-noise and often requires device retuning. We perform simulations of a charge sensor with an experimentally motivated noise model, which includes charge sensor drift. We introduce a method for calculating the charge sensor operating voltage as a function of elapsed time from a simple noise measurement, which allows us to deduce the reduction in readout fidelity in the absence of retuning. These calculations provide a simple framework for comparing device performance between different architectures and estimating experimental retuning times. |
Wednesday, March 8, 2023 12:54PM - 1:06PM |
N72.00008: Quantum Computation by Spin Parity Measurments with Encoded Spin Qubits Matthew Brooks, Charles Tahan Joint measurements of two-Pauli observables are a powerful tool for both the control and protection of quantum information. By following a simple recipe for measurement choices, single- and two- qubit rotations using two-Pauli parity and single qubit measurements are guaranteed to be unitary whilst requiring only a single ancilla qubit. Measurement based gates of this form keep the encoded qubits in their initial physical qubits and may be repeated unlike with resource state based measurement based quantum computing. This language for measurement based quantum computing is shown to be directly applicable to encoded double quantum dot singlet-triplet spin qubits, by measuring spin-parity between dots from neighboring qubits. Along with exchange interaction, a complete, leakage free, measurement based gate set can shown, up to a known Pauli correction. Measurements of this form provide a direct upgrade to previous methods of measurement based gates [1] by requiring exchange pulses and ancilla qubits. Both theoretical exact spin-parity measurements and previously experimentally demonstrated inexact spin-parity measurements are shown to useful for implementing the proposed measurement based scheme. This new method of spin qubit control offers a leakage-free, low resource overhead implementation of measurement-based control that is viable on current spin qubit |
Wednesday, March 8, 2023 1:06PM - 1:18PM |
N72.00009: Non-reciprocal Pauli Spin Blockade in a Silicon Double Quantum Dot David Ibberson, Theodor Lundberg, Jing Li, Louis Hutin, Jose Carlos Abadillo-Uriel, Michele Filippone, Benoit Bertrand, Andreas Nunnenkamp, Chang-Min Lee, Nadia Stelmashenko, Jason Robinson, Maud Vinet, Lisa Ibberson, Yann-Michel Niquet, Fernando Gonzalez-Zalba Spin qubits in gate-defined silicon quantum dots are receiving increased attention thanks to their potential for large-scale quantum computing. Readout of such spin qubits is done most accurately and scalably via Pauli spin blockade (PSB), however various mechanisms may lift PSB and complicate readout. In this work, we present an experimental observation of a new, highly prevalent PSB-lifting mechanism in a silicon double quantum dot due to incoherent tunnelling between different spin manifolds. Through dispersively-detected magnetospectroscopy of the double quantum dot in 16 charge configurations, we find the mechanism to be energy-level selective and non-reciprocal for neighbouring charge configurations. Additionally, using input-output theory we report a large coupling of different electron spin manifolds of 7.90 μeV, the largest reported to date, indicating an enhanced spin-orbit coupling which may enable all-electrical qubit control. |
Wednesday, March 8, 2023 1:18PM - 1:30PM |
N72.00010: Probing spin-orbit induced leakage mechanisms via electric dipole spin-resonance within Pauli spin-blockade towards efficient hole spin qubit control Joseph W Hillier, Ik Kyeong Jin, Scott D Liles, Aaquib Shamim, Isaac Vorreiter, Roy Li, Clement Godfrin, Stefan Kubicek, Kristiaan DeGreve, Alex R Hamilton Silicon quantum dot (QD) devices show immense promise as spin qubits by offering longer coherence times as a result of a weak hyperfine interaction on a readily scalable platform that utilizes complementary metal-oxide-semiconductor (CMOS) compatible fabrication processes. The advantageous spin-orbit interaction strength of holes further promotes this architecture by enabling high-frequency electric dipole spin-resonance (EDSR), in contrast to electrons which require on-chip axillary structures to induce such a coupling. However, the fundamental nature of spin-orbit coupling within hole QD systems is still not yet fully understood. |
Wednesday, March 8, 2023 1:30PM - 1:42PM |
N72.00011: Developing a Valley-Spin Readout Method in Bilayer WSe2 Michael Mastalish Qubits utilizing the valley pseudospin degree of freedom have the potential to serve as an attractive alternative to qubits that use electron spin exclusively. In this presentation, we discuss the design of bilayer WSe2 quantum dot devices that seek to take advantage of a novel valley-spin/charge conversion mechanism to determine valley-spin lifetimes in a dispersive readout scheme. Further consideration is given to the nanoscale fabrication techniques used, and we share our plans for the measurement and characterization of a valley-spin qubit using these devices. |
Wednesday, March 8, 2023 1:42PM - 1:54PM |
N72.00012: Trapping single photo-carriers in undoped single-gated quantum dots using an on-chip microwave resonator for charge readout Pierre Lefloic, Zhiren Wang, Alicia Kam, Louis Gaudreau, Michel Pioro-Ladrière Scaling up gate-defined quantum dot systems is hampered by the rapid growth in the number of control gates. To tackle this challenge, we propose a novel scheme, in which the quantum dots are created from optically generated charges trapped beneath accumulation gates. |
Wednesday, March 8, 2023 1:54PM - 2:06PM |
N72.00013: Measuring a quantum expectation value of a single qubit without collapse Jacob Hastrup, Morten Kjaergaard A well-known feature of quantum mechanics is that measurements on a single quantum state cannot provide full information about its quantum wave function. Determining the expectation value of a quantum observable thus in general requires many copies of the state. This suggests that the wavefunction is given empirical meaning only to an ensemble of identical states. In contrast to this view, Aharonov et al. [1] have proposed a scheme which, under certain conditions, allows one to measure the expectation values of arbitrary observables of a single state without collapsing the wave function. We present the experimental realization of such a protective measurement using a superconducting qubit platform. As an example, our experiment enables full tomographic reconstruction of a single quantum state. |
Wednesday, March 8, 2023 2:06PM - 2:18PM |
N72.00014: Non-local heat harvesting, refrigeration and thermometry based on triple quantum dot systems Aniket Singha, Suraj G Dhongade, Afreen A Haque, Anamika Barman Optimal non-local heat engines, refrigeration engines and thermometers based on dual quantum dots demand a sharp step-like transition in the energy-resolved system-to-reservoir coupling around the quantum dot ground states. Such an abrupt step-like change in the system-to-reservoir coupling cannot be achieved practically. Here, I discuss a realistic design for non-local heat engine, refrigeration engine and thermometer based on triple quantum dot set-up, that circumvents the necessity for any change in the system-to-reservoir coupling, demanded by the optimal dual dot setups. Proceeding further, I discuss the the performance of the triple dot set-up and point out that the set-up, when employed as heat and refrigeration engine, delivers approximately 50~70% performance of that of the optimal dual dot set-up. However, the triple dot thermometer surpasses the performance of the dual dot thermometer by a significant margin, in addition to sppressing thermometry induced drift in the target reservoir temperature. The novelty of the discussed triple dot set-up lies in fabrication simplicity along with reasonable performance, making it suitable for practical deployment as non-local heat engine, refrigeration engine and thermometer. |
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