Quantum Technology

Quantum theory was originally formulated as a statistical theory that describes ensembles of particles. Meanwhile, however, experiments in many laboratories around the world (and even by Google, IBM, Microsoft and Intel) have demonstrated quantum control over single particles. This has led to the dream of a “second quantum revolution”, in which the strangeness and the power of quantum physics is harnessed to facilitate novel technologies that provide possibilities beyond those offered by any classical device. In diverse settings, theory and proof-of-concept experiments have shown that one can gain unique advantage by storing, transmitting, and processing information encoded in systems that exhibit quantum properties. Examples include quantum cryptography (that allows for unbreakable encryption), quantum measurements (that can provide unprecedented resolution), quantum simulation (that can help to gain insight into complex quantum systems and materials), and quantum information processing (that can dramatically improve computational power for specific tasks).

This module will cover the basic principles that lie at the heart of the mentioned quantum technologies: The quantum harmonic oscillator and quantum two-level systems (qubits), generation and control of single photons and other quantum light fields, entanglement, decoherence, quantum measurement, experimental techniques for qubit control, quantum error correction, atomic clocks, quantum sensing, quantum communication, and the various types of quantum hardware used in current experiments.

After successful completion of the module the students are able to:

• Understand that the control and entanglement of quantum systems is a unique resource
• Mathematically describe quantum light fields, quantum bits and their coupling to one another
• Describe techniques to prepare, manipulate and measure quantum systems while avoiding decoherence
• Understand quantum logic operations and their experimental implementation
• Understand the open challenges towards the realization of quantum computers and other quantum technologies using current experimental platforms

No preconditions in addition to the requirements for the Master’s program in Physics.

The module cosists of a lecture and an exercise.

In the thematically structured lecture the learning content is presented. With cross references between different topics the universal concepts in Quantum technology are shown. In scientific discussions the students are involved to stimulate their analytic-physics intellectual power.

In the exercise the learning content is deepened and exercised using problem examples and calculations. Thus the students are able to explain and apply the learned physics knowledge independently.

Blackboard and PowerPoint presentation

Exercise sheets

S. Haroche & J.M. Raimond: Exploring the Quantum, ISBN 0198509146

Fox: Quantum Optics, ISBN 9780198566731

More literature recommendations are given in the lecture.

There will be an oral exam of 25 minutes duration. Therein the achievement of the competencies given in section learning outcome is tested exemplarily at least to the given cognition level using comprehension questions and sample calculations.

For example an assignment in the exam might be:

• Make a sketch of a control sequence that generates a maximally entangled state between two quantum bits.
• Explain how the individual steps of this control sequence can be implemented with superconducting qubits.
• Explain the main sources of decoherence for spin qubits in Silicon, and how this decoherence can be reduced by control and materials engineering.

Participation in the exercise classes is strongly recommended since the exercises prepare for the problems of the exam and rehearse the specific competencies.