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The detection of the quantum dot charge state using a quantum point contact charge detector has opened a new exciting route for the investigation of quantum dot devices in recent years. In particular, time-resolved charge detection allowed…

We theoretically consider the temporal dynamics of two coupled spin qubits (e.g., semiconductor quantum dots) driven by the inter-qubit spin-spin coupling. The presence of environmental noise (e.g., charge traps, nuclear spins, random…

Mesoscale and Nanoscale Physics · Physics 2016-07-29 S. Das Sarma , Robert E. Throckmorton , Yang-Le Wu

We study bifurcation measurement of a multi-level superconducting qubit using a nonlinear resonator biased in the straddling regime, where the resonator frequency sits between two qubit transition frequencies. We find that high-fidelity…

Quantum Physics · Physics 2012-09-27 Maxime Boissonneault , J. M. Gambetta , A. Blais

We report our study of the real-time charge counting statistics measured by a quantum point contact (QPC) coupled to a single quantum dot (QD) under different back-action strength. By tuning the QD-QPC coupling or QPC bias, we controlled…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 HaiOu Li , Ming Xiao , Gang Cao , Cheng Zhou , RuNan Shang , Tao Tu , GuangCan Guo , GuoPing Guo , HongWen Jiang

We study quantum tomography based on a stochastic continuous-time measurement record obtained from a probe field collectively interacting with an ensemble of identically prepared systems. In comparison to previous studies, we consider here…

Quantum Physics · Physics 2014-10-01 Robert L. Cook , Carlos A. Riofrío , Ivan H. Deutsch

We investigate the spin dynamics of a quantum dot with a spin-1/2 ground state in the Coulomb blockade regime and in the presence of a magnetic rf field leading to electron spin resonances (ESR). We show that by coupling the dot to leads,…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Hans-Andreas Engel , Daniel Loss

Single-shot measurement of the charge arrangement and spin state of a double quantum dot are reported, with measurement times down to ~ 100 ns. Sensing uses radio-frequency reflectometry of a proximal quantum dot in the Coulomb blockade…

Mesoscale and Nanoscale Physics · Physics 2010-04-27 C. Barthel , M. Kjaergaard , J. Medford , M. Stopa , C. M. Marcus , M. P. Hanson , A. C. Gossard

We investigate charge and spin transport through an adiabatically driven, strongly interacting quantum dot weakly coupled to two metallic contacts with finite bias voltage. Within a kinetic equation approach, we identify coefficients of…

Mesoscale and Nanoscale Physics · Physics 2015-06-11 Hernan L. Calvo , Laura Classen , Janine Splettstoesser , Maarten R. Wegewijs

As quantum dot (QD)-based spin qubits advance toward larger, more complex device architectures, rapid, automated device characterization and data analysis tools become critical. The orientation and spacing of transition lines in a charge…

Measurement backaction inherently alters observed dynamics in quantum physics. In the realm of quantum synchronization, this backaction induces a phase bias, making the assessment of synchronization critically dependent on the choice of the…

Quantum Physics · Physics 2024-06-28 Wataru Setoyama , Yoshihiko Hasegawa

High-efficiency single-photon detection in the microwave domain is a key enabling technology for quantum sensing, communication, and information processing. However, the extremely low energy of microwave photons (~{\mu}eV) presents a…

We investigate Kondo correlations in a quantum dot with normal and superconducting electrodes, where a spin bias voltage is applied across the device and the local interaction $U$ is either attractive or repulsive. When the spin current is…

Strongly Correlated Electrons · Physics 2018-06-13 Tie-Feng Fang , Ai-Min Guo , Qing-Feng Sun

Superconducting resonators coupled to solid-state qubits offer a scalable architecture for long-range entangling operations and fast, high-fidelity readout. Realizing this requires low photon-loss rates and qubits with tunable electric…

A common method for reading out the state of a spin qubit is by latching one logical qubit state, either $|1\rangle$ or $|0\rangle$, onto a different, metastable charge state. Such a latched state can provide a superior charge sensing…

Quantum measurements are described as instantaneous projections in textbooks. They can be stretched out in time using weak measurements, whereby one can observe the evolution of a quantum state as it heads towards one of the eigenstates of…

Quantum Physics · Physics 2018-04-11 Parveen Kumar , Suman Kundu , Madhavi Chand , R. Vijayaraghavan , Apoorva Patel

We measure the interdot charge relaxation time T_1 of a single electron trapped in an accumulation mode Si/SiGe double quantum dot. The energy level structure of the charge qubit is determined using photon assisted tunneling, which reveals…

Mesoscale and Nanoscale Physics · Physics 2014-08-27 K. Wang , C. Payette , Y. Dovzhenko , P. W. Deelman , J. R. Petta

We demonstrate the role of measurement back-action of a coherent spin environment on the dynamics of a spin (qubit) coupled to it, by inducing non-classical (Quantum Random Walk like) statistics on its measurement trajectory. We show how…

Quantum Physics · Physics 2019-08-14 D. D. Bhaktavatsala Rao , Sen Yang , Stefan Jesenski , Florian Kaiser , Jörg Wrachtrup

The simulation of complex quantum many-body systems is a promising short-term goal of noisy intermediate-scale quantum (NISQ) devices. However, the limited connectivity of native qubits hinders the implementation of quantum algorithms that…

Quantum Physics · Physics 2024-05-07 Andrea Solfanelli , Stefano Ruffo , Sauro Succi , Nicolò Defenu

We demonstrate coherent control and measurement of a superconducting qubit coupled to a superconducting coplanar waveguide resonator with a dynamically tunable qubit-cavity coupling strength. Rabi oscillations are measured for several…

Superconductivity · Physics 2011-11-16 Anthony J. Hoffman , Srikanth J. Srinivasan , Jay M. Gambetta , Andrew A. Houck

Hybrid devices based on the superconducting qubits have emerged as a promising platform for controlling the quantum states of macroscopic resonators. The nonlinearity added by a qubit can be a valuable resource for such control. Here we…

Mesoscale and Nanoscale Physics · Physics 2022-09-27 Sourav Majumder , Tanmoy Bera , Vibhor Singh