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Special IQUIST Seminar: Wolfgang Pfaff "Microwave photons for building and scaling quantum systems"

Event Type
Department of Physics
222 Loomis
Sep 26, 2019   11:00 am  
Wolfgang Pfaff, Microsoft Quantum Lab, Delft, The Netherlands
Marjorie Gamel
Originating Calendar
IQUIST Seminar Series

Interfacing quantum devices with traveling signals that can carry quantum information is essential for quantum information processing. For one, such signals are necessary for performing measurements; on the other hand, they can be used to achieve communication between isolated devices. Of particular interest are naturally interfaces with photons, which excel as carriers of quantum information. In my talk I will present the experimental realization of microwave photon interfaces based on circuit quantum electrodynamics (cQED). They have enabled us to perform novel quantum communication protocols and will be of essence for realizing a new quantum computing platform.

Superconducting cavities and qubits are well-established building blocks for small-scale quantum memories and processors. An ongoing challenge is to scale these systems without sacrificing their coherence. A promising way to achieve this scaling is to link small modules through traveling microwave photons. To this end we have realized an in-situ controllable interface for this conversion based on four-wave mixing [1]. This method has allowed us to realize deterministic quantum state transfer and entanglement between isolated superconducting quantum memories [2].

An emerging platform for fault-tolerant quantum computation is presented by topologically protected qubits based on recently observed Majorana zero modes (MZMs). An outstanding challenge is to find means to incorporate quantum measurement and control into devices that host them. We have realized hybrid devices based on quantum dots and superconducting resonators that can serve as a readout apparatus for MZM-based qubits. We are able to resolve proposed qubit signals with high accuracy on short time scales, paving the way for rf control and readout of topological qubits with microwaves [3,4].

[1] Pfaff, et al., Nat. Phys. 13, 882 (2017)
[2] Axline*, Burkhart*, Pfaff*, et al., Nat. Phys. 14, 705 (2018)
[3] De Jong, et al., Phys. Rev. Appl. 11, 044061 (2019)
[4] Van Veen et al., arXiv:1903.09066

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