Quantum computation: Fragile yet error-free

In a close collaborative effort, Spanish and Austrian physicists have experimentally encoded one quantum bit (qubit) in entangled states distributed over several particles and for the first time carried out simple computations on it. The 7-qubit quantum register could be used as the main building block for a quantum computer that corrects any type of error. The researchers’ results have now been published in Science.

On the horizon: A quantum internet

A team of scientists in Innsbruck, Austria, made an important step toward distributed quantum computing with cavities linking remote atom-based registers. They demonstrated precise control of the coupling of each of two trapped ions to the mode of an optical resonator.

An infallible quantum measurement

For quantum physicists, entangling quantum systems is one of their every day tools. Entanglement is a key resource for upcoming quantum computers and simulators. Now, physicists in Innsbruck and Geneva realized a new, reliable method to verify entanglement in the laboratory using a minimal number of assumptions about the system and measuring devices. Hence, this method witnesses the presence of useful entanglement. Their findings on this ‘verification without knowledge’ has been published in Nature Physics.

Entanglement enhanced detection of single-photon scattering events

In a new take on quantum logic spectroscopy, a sensitive spectroscopy method employing a Schrödinger cat state of motion is investigated. With sensitivity down to the single photon level, the new technique extends the range of transitions that can be investigate in the spectroscopy of atomic and molecular ions. The results of our work are published in the journal Nature Photonics.

Into the quantum internet at the speed of light

Not only do optical fibers transmit information every day around the world at the speed of light, but they can also be harnessed for the transport of quantum information. In the current issue of Nature Photonics, a research team of Innsbruck physicists led by Rainer Blatt and Tracy Northup report how they have directly transferred the quantum information stored in an atom onto a particle of light. Such information could then be sent over optical fiber to a distant atom.

Efficient and tunable interface for quantum networks

While several building blocks for a quantum computer have already been successfully tested in the laboratory, a network requires one additonal component: a reliable interface between computers and information channels. In the current issue of the journal Nature, physicists at the University of Innsbruck report the construction of an efficient and tunable interface for quantum networks.

Universal digital quantum simulation with trapped ions

The time evolution of a quantum system under the action of a Hamiltonian acting for a duration t can be simulated by a gate-based approach. Instead of trying to engineer the Hamiltonian of interest as it is done in the analog quantum simulation approach, the digital method is based on sequences of quantum gates that generate the same propagator as the Hamiltonian to be simulated for a given instance of time. By making use of the Trotter formula, very different Hamiltonians can be simulated with the same basic universal set of quantum gates as we demonstrated in an experiment with two to six ions.

Experimental repetitive quantum error correction

A team of physicists at the University of Innsbruck, led by Philipp Schindler and Rainer Blatt, has been the first to demonstrate a crucial element for a future functioning quantum computer: repetitive error correction. This allows scientists to correct errors occurring in a quantum computer efficiently. The researchers have published their findings in the scientific journal Science.

Calculations with 14 quantum bits

Once more Innsbruck physicists go beyond the limits of what is currently possible in quantum computation

Quantum physicists from the University of Innsbruck have set another world record: They have achieved controlled entanglement of 14 quantum bits (qubits) and, thus, realized the largest quantum register that has ever been produced. With this experiment the scientists have not only come closer to the realization of a quantum computer but they also show surprising results for the quantum mechanical phenomenon of entanglement.

Quantum simulator opens to the world

Austrian researchers realize a toolbox for open-system quantum simulation

Experimental physicists have put a lot of effort in isolating sensitive measurements from the disruptive influences of the environment. In an international first, Austrian quantum physicists have realized a toolbox of elementary building blocks for an open-system quantum simulator, where a controlled coupling to an environment is used in a beneficial way. This offers novel prospects for studying the behavior of highly complex quantum systems. The researchers have published their work in the scientific journal Nature.