Ani Nersisyan, Stefano Poletto, Nasser Alidoust, Riccardo Manenti, Russ Renzas, Cat-Vu Bui, Kim Vu, Tyler Whyland, Yuvraj Mohan, Eyob A. Sete, Sam Stanwyck, And… 展开作者
Ani Nersisyan, Stefano Poletto, Nasser Alidoust, Riccardo Manenti, Russ Renzas, Cat-Vu Bui, Kim Vu, Tyler Whyland, Yuvraj Mohan, Eyob A. Sete, Sam Stanwyck, Andrew Bestwick, Matthew Reagor
Enabling applications for solid state quantum technology will require systematically reducing noise, particularly dissipation, in these systems. Yet, when multiple decay channels are present in a system with similar weight, resolution to distinguish relatively small changes is necessary to infer improvements to noise levels. For superconducting qubits, uncontrolled variation of nominal performance makes obtaining such resolution challenging. Here, we approach this problem by investigating specific combinations of previously reported fabrication techniques on the quality of 242 thin film superconducting resonators and qubits. Our results quantify the influence of elementary processes on dissipation at key interfaces. We report that an end-to-end optimization of the manufacturing process that integrates multiple small improvements together can produce an average ${\overline{T}_{1}=76\pm13~μ}$s across 24 qubits with the best qubits having ${T_1\geq110~μ}$s. Moreover, our analysis places bounds on energy decay rates for three fabrication-related loss channels present in state-of-the-art superconducting qubits. Understanding dissipation through such systematic analysis may pave the way for lower noise solid state quantum computers.
Learning Lindblad Dynamics of a Superconducting Quantum Processor
University of Copenhagen（哥本哈根大学）；Niels Bohr Institute, University of Copenhagen（尼尔斯·玻尔研究所，哥本哈根大学）；Center for the Mathematics of Quantum Theory, MATH Department, University of Copenhagen（哥本哈根大学数学系量子理论数学中心）；Chalmers University of Technology（查尔姆斯理工大学）
From GDSII to Wafer: EDA Design Flow and Data Conversion for Wafer-Scale Manufacturing of Superconducting Quantum Chips
Yangtze Delta Industrial Innovation Center of Quantum Science and Technology（量子科学与技术长三角产业创新中心）；China Academy of Electronics and Information Technology（中国电子科技集团公司）
The D-wave processor is a partially controllable open quantum system which exchanges energy with its surrounding environment (in the form of heat) and with the external time dependent control fields (in the form of work). Despite being rarely thought as such, it is a thermodynamic machine. Here we investigate the properties of the D-Wave quantum annealers from a thermodynamical perspective. We performed a number of reverse-annealing experiments on the D-Wave 2000Q via the open access cloud server Leap, with the aim of understanding what type of thermal operation the machine performs, and quant…
Numerical Modeling of Quasiparticle-Induced Dissipation in Fluxonium Qubits
Lincoln Laboratory, Massachusetts Institute of Technology（林肯实验室，麻省理工学院）；Research Laboratory of Electronics, Massachusetts Institute of Technology（电子研究实验室，麻省理工学院）；Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology（电气工程和计算机科学系，麻省理工学院）
The quantum kernel method results clearly outperformed a classical SVM when analyzing low-resolution images with minimal feature selection on the quantum simulator, with inconsistent results when run on an actual quantum processor. We chose to use an existing quantum kernel method for classification. We applied dynamic decoupling error mitigation using the Mitiq package to the Quantum SVM kernel method, which, to our knowledge, has never been done for quantum kernel methods for image classification. We applied the quantum kernel method to classify real world image data from a manufacturing fac…
We show how "single" quantum dots, each hosting a singlet-triplet qubit, can be placed in arrays to build a spin quantum cellular automaton. A fast ($\sim 10$ ns) deterministic coherent singlet-triplet filtering, as opposed to current incoherent tunneling/slow-adiabatic based quantum gates (operation time $\sim 300$ ns), can be employed to produce a two-qubit gate through capacitive (electrostatic) coupling that can operate over significant distances. This is the coherent version of the widely discussed charge and nano-magnet cellular automata and would offer speed, reduce dissipation, perform…
We have developed a quantum annealing processor, based on an array of tunably coupled rf-SQUID flux qubits, fabricated in a superconducting integrated circuit process [1]. Implementing this type of processor at a scale of 512 qubits and 1472 programmable inter-qubit couplers and operating at ~ 20 mK has required attention to a number of considerations that one may ignore at the smaller scale of a few dozen or so devices. Here we discuss some of these considerations, and the delicate balance necessary for the construction of a practical processor that respects the demanding physical requirement…
Design and Benchmarking of a Quantum Photonic Chip
Rotonium S.r.l.（罗托尼乌斯有限公司）；Centre for Quantum Technologies, National University of Singapore（新加坡国立大学量子技术中心）；Inveriant Pte. Ltd.（因维安特私人有限公司）；Department of Electronics, Information and Bioengineering, Politecnico di Milano（米兰理工大学电子、信息与生物工程系）；Photonic Networks e Technologies National Laboratory, CNIT（意大利国家理工学院光子网络与技术国家实验室）
The efficient simulation of quantum systems is a primary motivating factor for developing controllable quantum machines. For addressing systems with underlying bosonic structure, it is advantageous to utilize a naturally bosonic platform. Optical photons passing through linear networks may be configured to perform quantum simulation tasks, but the efficient preparation and detection of multiphoton quantum states of light in linear optical systems are challenging. Here, we experimentally implement a boson sampling protocol for simulating molecular vibronic spectra [Nature Photonics $\textbf{9}$…
Solid-state quantum computers require classical electronics to control and readout individual qubits and to enable fast classical data processing [1-3]. Integrating both subsystems at deep cryogenic temperatures [4], where solid-state quantum processors operate best, may solve some major scaling challenges, such as system size and input/output (I/O) data management [5]. Spin qubits in silicon quantum dots (QDs) could be monolithically integrated with complementary metal-oxide-semiconductor (CMOS) electronics using very-large-scale integration (VLSI) and thus leveraging over wide manufacturing …
We investigate the continuous-time dynamics of highly-entangling intermediate-scale quantum circuits in the presence of dissipation and decoherence. By compressing the Hilbert space to a time-dependent "corner" subspace that supports faithful representations of the density matrix, we simulate a noisy quantum Fourier transform processor with up to 21 qubits. Our method is efficient to compute with a controllable accuracy the time evolution of intermediate-scale open quantum systems with moderate entropy, while taking into account microscopic dissipative processes rather than relying on digital …
Error accumulation in dissipative quantum circuits
Universidad Autónoma de Madrid（马德里自治大学）；Instituto Superior Técnico, Universidade de Lisboa（里斯本大学高级理工学院）；University of Stuttgart（斯图加特大学）；Jagiellonian University（雅盖隆大学）；Polish Academy of Sciences（波兰科学院）；OsloMet – Oslo Metropolitan University（奥斯陆都会大学）
Quantum information processing rests on our ability to manipulate quantum superpositions through coherent unitary transformations. In reality the quantum information processor (a linear ion trap, or cavity qed implementation for example) exists in a dissipative environment. Dephasing, and other technical sources of noise, as well as more fundamental sources of dissipation severely restrict quantum processing capabilities. The strength of the coherent coupling needed to implement quantum logic is not always independent of dissipation. The limitations these dissipative influences present will be…
Yangtze Delta Industrial Innovation Center of Quantum Science and Technology（量子科学与技术长三角产业创新中心）；China Academy of Electronics and Information Technology（中国电子科技集团公司）
In chemical reactions, the interplay between coherent evolution and dissipation is central to determining key properties such as the rate and yield. Of particular interest are cases where two potential energy surfaces cross at features known as conical intersections (CIs), resulting in nonadiabatic dynamics that may promote ultrafast and highly efficient reactions when rovibrational damping is present. A prominent chemical reaction that involves a CI is the cis-trans isomerization reaction in rhodopsin, which is crucial to vision. CIs in real molecular systems are typically investigated via op…
Silicon quantum dot spin qubits provide a promising platform for large-scale quantum computation because of their compatibility with conventional CMOS manufacturing and the long coherence times accessible using $^{28}$Si enriched material. A scalable error-corrected quantum processor, however, will require control of many qubits in parallel, while performing error detection across the constituent qubits. Spin resonance techniques are a convenient path to parallel two-axis control, while Pauli spin blockade can be used to realize local parity measurements for error detection. Despite this, sili…
A hybrid quantum computing scheme is studied where the hybrid qubit is made of an ion trap qubit serving as the information storage and a solid-state charge qubit serving as the quantum processor, connected by a superconducting cavity. In this paper, we extend our previous work [1] and study the decoherence, coupling and scalability of the hybrid system. We present our calculations of the decoherence of the coupled ion - charge system due to the charge fluctuations in the solid-state system and the dissipation of the superconducting cavity under laser radiation. A gate scheme that exploits rap…
Superconducting integrated circuits have demonstrated a tremendous potential to realize integrated quantum computing processors. However, the downside of the solid-state approach is that superconducting qubits suffer strongly from energy dissipation and environmental fluctuations caused by atomic-scale defects in device materials. Further progress towards upscaled quantum processors will require improvements in device fabrication techniques which need to be guided by novel analysis methods to understand and prevent mechanisms of defect formation. Here, we present a new technique to analyse ind…
We develop an architecture of hybrid quantum solid-state processing unit for universal quantum computing. The architecture allows distant and nonidentical solid-state qubits in distinct physical systems to interact and work collaboratively. All the quantum computing procedures are controlled by optical methods using classical fields and cavity QED. Our methods have prominent advantage of the insensitivity to dissipation process benefiting from the virtual excitation of subsystems. Moreover, the QND measurements and state transfer for the solid-state qubits are proposed. The architecture opens …
A robust cryogenic infrastructure in form of a wired, thermally optimized dilution refrigerator is essential for present and future solid-state based quantum processors. Here, we engineer an extensible cryogenic setup, which minimizes passive and active heat loads, while guaranteeing rapid qubit control and readout. We review design criteria for qubit drive lines, flux lines, and output lines used in typical experiments with superconducting circuits and describe each type of line in detail. The passive heat load of stainless steel and NbTi coaxial cables and the active load due to signal dissi…
In the near future, a major challenge in quantum computing is to scale up robust qubit prototypes to practical problem sizes and to implement comprehensive error correction for computational precision. Due to inevitable quantum uncertainties in resonant control pulses, increasing the precision of quantum gates comes with the expense of increased energy consumption. Consequently, the power dissipated in the vicinity of the processor in a well-working large-scale quantum computer seems unacceptably large in typical systems requiring low operation temperatures. Here, we introduce a method for qub…
Low-loss waveguides are required for quantum communication at distances beyond the chip-scale for any low-temperature solid-state implementation of quantum information processors. We measure and analyze the attenuation constant of commercially available microwave-frequency waveguides down to millikelvin temperatures and single photon levels. More specifically, we characterize the frequency-dependent loss of a range of coaxial and rectangular microwave waveguides down to $0.005\,\rm{dB}/\rm{m}$ using a resonant-cavity technique. We study the loss tangent and relative permittivity of commonly us…
The scaleup of quantum computers operating in the microwave domain requires advanced control electronics, and the use of integrated components that operate at the temperature of the quantum devices is potentially beneficial. However, such an approach requires ultra-low power dissipation and high signal quality in order to ensure quantum-coherent operations. Here, we report an on-chip device that is based on a Josephson junction coupled to a spiral resonator and is capable of coherent continuous-wave microwave emission. We show that characteristics of the device accurately follow a theory based…
Ultralow-power coherent qubit control using AQFP logic at millikelvin temperatures
RIKEN（理化学研究所）；Tokyo University of Science（东京科学大学）；The University of Tokyo（东京大学）；National Institute of Advanced Industrial Science and Technology (AIST)（国立产业技术综合研究所）；Tohoku University（东北大学）；Yokohama National University（横滨国立大学）；Kobe University（神户大学）
Silicon nanoelectronic devices can host single-qubit quantum logic operations with fidelity better than 99.9%. For the spins of an electron bound to a single donor atom, introduced in the silicon by ion implantation, the quantum information can be stored for nearly 1 second. However, manufacturing a scalable quantum processor with this method is considered challenging, because of the exponential sensitivity of the exchange interaction that mediates the coupling between the qubits. Here we demonstrate the conditional, coherent control of an electron spin qubit in an exchange-coupled pair of $^{…
Once called a "classically non-describable two-valuedness" by Pauli , the electron spin is a natural resource for long-lived quantum information since it is mostly impervious to electric fluctuations and can be replicated in large arrays using silicon quantum dots, which offer high-fidelity control. Paradoxically, one of the most convenient control strategies is the integration of nanoscale magnets to artificially enhance the coupling between spins and electric field, which in turn hampers the spin's noise immunity and adds architectural complexity. Here we demonstrate a technique that enables…
One of the main limitations in state-of-the art solid-state quantum processors are qubit decoherence and relaxation due to noise in their local environment. For the field to advance towards full fault-tolerant quantum computing, a better understanding of the underlying microscopic noise sources is therefore needed. Adsorbates on surfaces, impurities at interfaces and material defects have been identified as sources of noise and dissipation in solid-state quantum devices. Here, we use an ultra-high vacuum package to study the impact of vacuum loading, UV-light exposure and ion irradiation treat…
