Related papers: Simultaneous readout of two charge qubits
We present a new way of continuously reading-out the state of a single electronic spin. Our detection scheme is based on an exchange interaction between the electronic spin and a nearby read-out quantum dot. The coupling between the two…
Common flux qubit readout schemes are qubit dominated, meaning they measure in the energy eigenbasis of the qubit. For various applications meausrements in a basis different from the energy eigenbasis are required. Here we present an…
We present measurements on a quantum dot and a nearby, capacitively coupled, quantum point contact used as a charge detector. With the dot being weakly coupled to only a single reservoir, the transfer of individual electrons onto and off…
We explore the full counting statistics of single electron tunneling through a quantum dot using a quantum point contact as non-invasive high bandwidth charge detector. The distribution of counted tunneling events is measured as a function…
We observe measurement-induced qubit state mixing in a transmon qubit dispersively coupled to a planar readout cavity. Our results indicate that dephasing noise at the qubit-readout detuning frequency is up-converted by readout photons to…
Single electron transistors (SETs) are very sensitive electrometers and they can be used in a range of applications. In this paper we give an introduction to the SET and present a full quantum mechanical calculation of how noise is…
We present a method for measuring the internal state of a superconducting qubit inside an on-chip microwave resonator. We show that one qubit state can be associated with the generation of an increasingly large cavity coherent field, while…
The implementation of a quantum computer requires a qubit-specific measurement capability to read-out the final state of a quantum system. The model of spin dependent tunneling followed by charge readout has been highly successful in…
The "quantronium" is a superconducting qubit consisting of a split Cooper pair box in which a large tunnel junction is inserted. This circuit has a special bias point where the Larmor frequency is, to first order, insensitive to…
We study the quantum charge noise and measurement properties of the double Cooper pair resonance point in a superconducting single-electron transistor (SSET) coupled to a Josephson charge qubit. Using a density matrix approach for the…
A simple theory of the detected current I(t) flowing through charge qubits -- quantum dots -- is proposed in terms of standard continuous measurement theory. Applied to a double dot, our formalism easily confirms previous results on quantum…
We identify a novel mechanism to read out a single solid-state electron spin using an all-electrical spin-to-charge conversion in a closed system. Our scheme uses three donors and two electron spins, one spin is the qubit, the other is a…
Measurement is an essential component of quantum algorithms, and for superconducting qubits it is often the most error prone. Here, we demonstrate model-based readout optimization achieving low measurement errors while avoiding detrimental…
Single-shot qubit readout typically combines high readout contrast with long-lived readout signals, leading to large signal-to-noise ratios and high readout fidelities. In recent years, it has been demonstrated that both readout contrast…
The charge transfer statistics of a tunnel junction coupled to a quantum object is studied using the charge projection technique. The joint dynamics of the quantum object and the number of charges transferred through the junction is…
In this paper, we study the quantum decoherence induced by accumulation of electron tunnelings during the quantum measurement of a charge qubit. The charge qubit is a single electron confined in coupled quantum dots. The measurement of the…
We report on the realization of a coupled quantum dot (QD) system containing two single QDs made in two adjacent InAs nanowires. One QD (sensor QD) is used as a charge sensor to detect the charge state transition in the other QD (target…
A process tomography based optimization scheme for open quantum systems is used to determine the performance limits of Josephson charge qubits within current experimental means. The qubit is modeled microscopically as an open quantum system…
Detecting quasiparticle tunneling events in superconducting circuits provides information about the population and dynamics of non-equilibrium quasiparticles. Such events can be detected by monitoring changes in the frequency of an…
A theory of electron counting statistics in quantum transport is presented. It involves an idealized scheme of current measurement using a spin 1/2 coupled to the current so that it precesses at the rate proportional to the current. Within…