Error message

Deprecated function: The each() function is deprecated. This message will be suppressed on further calls in _menu_load_objects() (line 579 of /home/equsorg/public_sqd/includes/

Circuit QED architecture for quantum control and measurement

Strong interaction between artificial atoms (qubits or qutrits) and microwave photons in a cavity gave birth one of the leading platforms for quantum control and computing, called circuit Quantum Electrodynamics (QED). In these systems the superconducting qubits based on Josephson junctions are manipulated with local magnetic and electric fields while the resonators serve a as quantum bus and for read out of the qubit quantum states.

In the past our group members have strongly contributed to implementing key elements for quantum information processing with the superconducting circuits. This includes the first implementations of: the gap tunable flux qubit1, multiplex read out of multi-qubit sample2, the three-qubit Toffoli gate3 and quantum teleportation in solid state4.

At UQ we continue to investigate new regimes of circuit QED systems to get a better grip on quantum mechanics. To perform experiments in this field our laboratory has installed a sophisticated measurement appartus with extensive list of the microwave and digital electronics, custom build measurement software with unlimited functionality and parametric amplifiers.

  1. F.G. Paauw, A. Fedorov, C.J.P.M. Harmans, and J.E. Mooij, Tuning the gap of a superconducting flux qubit, Phys. Rev. Lett. 102, 090501 (2009).

  2. M. Jerger, S. Poletto, P. Macha, U. Hübner, A. Lukashenko, E. Il'ichev and A. V. Ustinov, Readout of a qubit array via a single transmission line, EPL 96, 40012 (2011).

  3. A. Fedorov, L. Steffen, M. Baur, M. P. da Silva and A. Wallraff, Implementation of a Toffoli gate with superconducting circuits, Nature 481, 170 (2012).

  4. L. Steffen, Y. Salathe, M. Oppliger, P. Kurpiers, M. Baur, C. Eichler, G. Puebla-Hellmann, A. Fedorov  and A. Wallraff, Realization of deterministic quantum teleportation with solid state qubits, Nature 500, 319 (2013).

Information as fuel for a quantum clock

Information as Fuel for a Quantum Clock is funded by Foundational Questions Institute. This is a collaboration between SQDLab, a theory group of Prof. G. Milburn and a Dr. S. Shrapnel providing a philosophical support of the project. The project is dedicated to study of fundamental quantum limits of time keeping and equivalence of information and fuel for a quantum clock.

The ARC Centre of Excellence for Engineered Quantum Systems

This Centre of Excellence seeks to initiate the Quantum Era in the 21st century by engineering designer quantum systems.

Jerger M. et al, 2016
Nature Communications, 7, pp. 12930

Contextuality is one of the most fundamental properties of quantum mechanics, distinguishing it from classical physics without a need for nonlocality or entanglement. It is also a critical resource for exponential speedup in universal surface-code quantum computing. Our result is the first experiment violating a noncontextuality inequality with an indivisible system where entanglement cannot be defined which also addresses all known major loopholes, such as the detection, compatibility and individual-existence loopholes. Violating noncontextuality with superconducting circuits, a leading candidate for implementing surface-code quantum computing, comprises an important conceptual milestone in demonstrating their suitability for quantum technological applications.

We discuss a similarity between resonant oscillations in two nonlinear systems; namely, a chain 
of coupled Duffing oscillators and a bilayer fish-scale metamaterial. In such systems two

Macha Pascal et al, 2014
Nature Communications, 5, pp. 5146

Implementation of a quantum metamaterial using superconducting qubits