No real physical system is ever perfectly isolated from its surroundings and quantum systems are no exception. The theory of open quantum systems studies the evolution of quantum systems interacting with an external environment. Well-known phenomena such as quantum decoherence, atomic spontaneous emission, or superradiance can be understood under the framework of open quantum systems. Moreover, this theory is a necessary tool to understand the thermodynamics of quantum systems in contact with thermal reservoirs, broadly known as quantum thermodynamics.
At HelTeq we are very interested in open quantum systems and, in particular, we focus on the characterization of master equations for studying their dynamics, on their compatibility with the laws of thermodynamics, and on quantum thermalization, i.e., on the process through which quantum systems reach an equilibrium state. We also study the emergence of open quantum systems in circuit quantum electrodynamics (circuit QED), the theory behind superconducting qubits, which are the fundamental units of most of the current quantum computers. To build a bridge between experimental and theoretical research, we actively collaborate with different experimental groups at Aalto University (mostly the PICO and KVANTTI groups) on open systems in circuit QED.
Measurements are a fundamental part of quantum mechanics, allowing the extraction of information about a system's state and introducing new phenomenology and paradoxes, still demanding a widely accepted explanation today. Moreover, as measurements lay at the intersection between the classical and the quantum world, a resolution of the so-called measurement problem should also address some issues concerning the quantum-to-classical crossover.
Quantum gravity studies one specific case of the interplay between classical and quantum physics, i.e. between general relativity and quantum mechanics. In this way, quantum gravity aims to construct a unique description of our universe's microscopic and macroscopic features. However, research in quantum gravity usually considers neither measurements nor their effect upon measured systems, hence taking a limited approach to the problem.
At HelTeq, we explore the consequences of including measurements in QFT and quantum gravity. Our approach is operational: we consider measurement devices interacting with measured systems, study the information transfer from the latter to the former and model the measurement-induced state collapses as a local non-unitary process. This way, we look at state collapses in QFT and low-energy quantum gravity scenarios, and study measurements' back-reaction on spacetimes in the semi-classical regime and holography, in collaboration with Doc. Esko Keski-Vakkuri at the University of Helsinki.
Quantum computing harnesses the principles of quantum mechanics to execute specific tasks more efficiently than classical computers. Simulating the dynamics of quantum systems is one of these tasks, which is notoriously a formidable challenge for classical machines. Quantum simulation thus stands out as one of the most promising fields within quantum technologies. At Helteq we are interested in different aspects of quantum simulation, with a focus on open quantum system dynamics and on the evaluation of its performance on contemporary quantum devices available on the cloud, commonly referred to as near-term quantum computers.
In the realm of quantum computing, the development of efficient and scalable quantum algorithms is a central concern. Apart from designing algorithms for open quantum system simulation, at Helteq we have studied the spatial search algorithm based on continuous-time quantum walks, and we are currently starting to explore the quantum approximate optimization algorithm (QAOA), which is specifically designed for execution on near-term quantum computers.
Quantum technologies could help us revolutionise several fields, from healthcare to energetic and environmental. To keep up with this — potentially disruptive — transformation, academic education plays a key role, but it is equally relevant to educate society about quantum science at all levels.
In the group, we create and curate innovative educational resources on quantum science and technologies diversified into the languages of various target groups, from school students to industry professionals. Regardless of the context and background of the learner, we believe that playfulness is a powerful tool to build intuition and maintain engagement. For this reason, we use a variety of media, interactive elements, and even games to enhance the effectiveness of the learning process, while remaining grounded on scientific correctness. In addition, we organise and participate in outreach events for schools and the general public and workshops to foster the contamination between quantum science and other fields.
Multimedia resources and information on the initiatives are all accessible on QPlayLearn's online platform.