PhD and Post Doc Quantum Seminar Series: Joseph Minnella & Robert Spivey

This Spring semester the QUIEST Center is continuing to expand its new seminar series geared towards PhD and Post Doc students across SEAS and SAS to present on quantum-related topics of their choosing. Read on for more information on this week’s seminar presentations:

First Presentation by:

Joseph Minnella, PhD student in Physics

Talk Title: 

Dynamical Decoupling for Multi-Qubit Control and Entanglement

Description:

Spins in solid state hosts can function as multi-qubit registers and are one of the leading platforms for nodes in future quantum networks. Although coherence times are long, even at room temperature, they are ultimately limited by interactions with the spin bath. One path to extending coherence times involves dynamically decoupling (DD) the central spin from the bath. Additionally, these DD sequences can be used for multi-qubit control and entanglement generation. In this talk, I’ll present our work in the Quantum Engineering Laboratory to detect and control 4 nuclear spin qubits surrounding the Nitrogen Vacancy center in diamond at room temperature using these techniques.

Second Presentation by:

Robert Spivey, Postdoc in ESE

Talk Title:

Shuttling electrons between Si/SiGe quantum dots using resistive top gate

Description:

Semiconductor quantum dot qubits have reached the error threshold regime, yet many scaling challenges remain. To support the network topologies needed for quantum error correction coherent transport of spin qubits between quantum processing regions is required. Spin qubit shuttling schemes demonstrated to date rely on patterned interdigitated gates across the length of the shuttle lowering fabrication yield. We present a novel device which could simplify the structure needed to achieve coherent qubit shuttling. Two double quantum dots (DQD) with accompanying sensor dots are connected by a ~12 μm Niobium silicon (NbSi) top gate, a material chosen for its high resistivity at millikelvin temperatures. The NbSi top gate connecting the DQDs creates a channel which can store charge, and be emptied of charge allowing a path for single electrons to travel. The large resistivity allows for a potential difference to be established imparting a force on single charges while adding minimally to the heat load. In theory nanosecond scale transit times can be achieved. Two designs are discussed and initial data is presented about the behavior of the device.