Hamiltonian Engineering with Multicolor Drives for Fast Entangling Gates and Quantum Crosstalk Cancellation.

Quantum computers built with superconducting artificial atoms already stretch the limits of their classical counterparts. While the lowest energy states of these artificial atoms serve as the qubit basis, the higher levels are responsible for both a host of attractive gate schemes as well as generating undesired interactions. In particular, when coupling these atoms to generate entanglement, the higher levels cause shifts in the computational levels that lead to unwanted ZZ quantum crosstalk.

High-performance superconducting quantum processors via laser annealing of transmon qubits.

Scaling the number of qubits while maintaining high-fidelity quantum gates remains a key challenge for quantum computing. Presently, superconducting quantum processors with >50 qubits are actively available. For these systems, fixed-frequency transmons are attractive because of their long coherence and noise immunity.

Demonstration of a High-Fidelity cnot Gate for Fixed-Frequency Transmons with Engineered ZZ Suppression.

Improving two-qubit gate performance and suppressing cross talk are major, but often competing, challenges to achieving scalable quantum computation. In particular, increasing the coupling to realize faster gates has been intrinsically linked to enhanced cross talk due to unwanted two-qubit terms in the Hamiltonian. Here, we demonstrate a novel coupling architecture for transmon qubits that circumvents the standard relationship between desired and undesired interaction rates.

Tunable Coupling Architecture for Fixed-Frequency Transmon Superconducting Qubits.

Implementation of high-fidelity 2-qubit operations is a key ingredient for scalable quantum error correction. In superconducting qubit architectures, tunable buses have been explored as a means to higher-fidelity gates. However, these buses introduce new pathways for leakage.

Experimental Demonstration of a Resonator-Induced Phase Gate in a Multiqubit Circuit-QED System.

The resonator-induced phase (RIP) gate is an all-microwave multiqubit entangling gate that allows a high degree of flexibility in qubit frequencies, making it attractive for quantum operations in large-scale architectures. We experimentally realize the RIP gate with four superconducting qubits in a three-dimensional circuit-QED architecture, demonstrating high-fidelity controlled-z (cz) gates between all possible pairs of qubits from two different 4-qubit devices in pair subspaces. These qubits are arranged within a wide range of frequency detunings, up to as large as 1.

Charge noise spectroscopy using coherent exchange oscillations in a singlet-triplet qubit.

Two level systems that can be reliably controlled and measured hold promise as qubits both for metrology and for quantum information science. Since a fluctuating environment limits the performance of qubits in both capacities, understanding environmental coupling and dynamics is key to improving qubit performance. We show measurements of the level splitting and dephasing due to the voltage noise of a GaAs singlet-triplet qubit during exchange oscillations.

Demonstration of entanglement of electrostatically coupled singlet-triplet qubits.

Quantum computers have the potential to solve certain problems faster than classical computers. To exploit their power, it is necessary to perform interqubit operations and generate entangled states. Spin qubits are a promising candidate for implementing a quantum processor because of their potential for scalability and miniaturization.

Anomalous structure in the single particle spectrum of the fractional quantum Hall effect.

The two-dimensional electron system is a powerful laboratory for investigating the physics of interacting particles. Application of a large magnetic field produces massively degenerate quantum levels known as Landau levels; within a Landau level the kinetic energy of the electrons is suppressed, and electron-electron interactions set the only energy scale. Coulomb interactions break the degeneracy of the Landau levels and can cause the electrons to order into complex ground states.

Diffractive lens fabricated with binary features less than 60 nm.

We designed, fabricated, and characterized a binary diffractive lens with features less than 60 nm. The lens was designed for operation in the red portion of the spectrum. Experimental measurements of lens performance agree with predictions generated by rigorous models of diffraction.

High-resolution spectroscopy of two-dimensional electron systems.

Spectroscopic methods involving the sudden injection or ejection of electrons in materials are a powerful probe of electronic structure and interactions. These techniques, such as photoemission and tunnelling, yield measurements of the 'single-particle' density of states spectrum of a system. This density of states is proportional to the probability of successfully injecting or ejecting an electron in these experiments.

Endocrine and ovulatory responses of the gilt to exogenous gonadotropins and estradiol during sexual maturation.

Three studies were conducted to investigate the endocrine and ovulatory responses of the prepubertal gilt to exogenous estradiol and gonadotropins. In Study One, prepubertal gilts of 190 days of age were injected s.c.

Estrous behavior and circadian discharge of luteinizing hormone in the prepubertal gilt in response to exogenous estrogen.

The influence of varying doses of estradiol benzoate (EB) on the induction of estrus and luteinizing hormone (LH) discharge was studied in crossbred prepubertal gilts of 135 to 150 days of age. Five gilts were assigned randomly to each of 6 groups and treated with 0, 10, 20, 100 or 200 micrograms EB/kg body weight (BW) at 1200 h or with 10 micrograms/kg at 2400 h. The characteristics of the estrous and endocrine responses of the prepubertal gilts to EB were compared to the responses of 4 ovariectomized, adult gilts treated with EB.