Final Report Summary - QIOS (Quantum Interfaces and Open Systems)
Quantum information processing aims at processing information in a completely new way. Creating quantum computers based on quantum mechanical bits, so-called qubits, may in principle allow solving computational tasks, which are impossible to solve with the computers we know today. A major obstacle to these possibilities comes from the fact that every physical system is to some degree an open system interacting with its environment. Normally, this spoils many of the interesting quantum effects that one is trying to exploit. Contrary to this we have developed theories for how to exploit the fact that quantum systems are open, and use this as a resource for quantum information processing.
We have shown how the interaction with the environment can be exploited to realize quantum mechanically entangled state. These can be an important resource for quantum information processing. As a part of this project, we collaborated with an experimental group on using the interaction with the environment to entangle two trapped ions. This is the first time a maximally entangled state of two qubits has been created in this way and represents a step towards a completely different approach to realizing quantum information processing. We have generalized these theories to multi-particle entanglement and error correction codes, which may be important resources for future quantum technologies.
The fact that quantum systems are open also means that they can exchange information with their surroundings. This is particularly interesting for quantum communication, which aims at using the laws of quantum mechanics for communication. To realize this, it is essential that local processors can exchange information between them, and thus they need to be open systems. In practice this exchange of information happens through light. We have developed theories for how to interface material qubits with light and use this for quantum information processing. Specifically we have developed theories for how to use the coupling of quantum dots to light for quantum information processing and how in this case the information can be protected from harmful interactions with the environment. We have developed theories for how to connect some of the world’s most advanced quantum computers (super conducting qubits) to light in order to enable quantum communication. Also, we have shown how a novel effect called motional averaging, can enable long distance quantum communication by storing information in room temperature clouds of atoms.
The coupling of light and material qubits also opens up new possibilities for processing information encoded in light. We have developed theories for how to exploit the coupling for this purpose. This is achieved by coupling light to clouds of atoms and either exploiting the interaction among highly excited (Rydberg) states of the atoms or by slowing down the light to a stand-still in order to enhance the interaction between different light pulses.
Finally, a detailed understanding of the open system dynamics and the coupling to the environment is essential for assessing the performance of future quantum technologies. Exploiting our understanding of the open system dynamics, we have developed theories for how to use entanglement to enhance the performance of the world’s most accurate atomic clocks despite the presence of unwanted interactions with the environment.
We have shown how the interaction with the environment can be exploited to realize quantum mechanically entangled state. These can be an important resource for quantum information processing. As a part of this project, we collaborated with an experimental group on using the interaction with the environment to entangle two trapped ions. This is the first time a maximally entangled state of two qubits has been created in this way and represents a step towards a completely different approach to realizing quantum information processing. We have generalized these theories to multi-particle entanglement and error correction codes, which may be important resources for future quantum technologies.
The fact that quantum systems are open also means that they can exchange information with their surroundings. This is particularly interesting for quantum communication, which aims at using the laws of quantum mechanics for communication. To realize this, it is essential that local processors can exchange information between them, and thus they need to be open systems. In practice this exchange of information happens through light. We have developed theories for how to interface material qubits with light and use this for quantum information processing. Specifically we have developed theories for how to use the coupling of quantum dots to light for quantum information processing and how in this case the information can be protected from harmful interactions with the environment. We have developed theories for how to connect some of the world’s most advanced quantum computers (super conducting qubits) to light in order to enable quantum communication. Also, we have shown how a novel effect called motional averaging, can enable long distance quantum communication by storing information in room temperature clouds of atoms.
The coupling of light and material qubits also opens up new possibilities for processing information encoded in light. We have developed theories for how to exploit the coupling for this purpose. This is achieved by coupling light to clouds of atoms and either exploiting the interaction among highly excited (Rydberg) states of the atoms or by slowing down the light to a stand-still in order to enhance the interaction between different light pulses.
Finally, a detailed understanding of the open system dynamics and the coupling to the environment is essential for assessing the performance of future quantum technologies. Exploiting our understanding of the open system dynamics, we have developed theories for how to use entanglement to enhance the performance of the world’s most accurate atomic clocks despite the presence of unwanted interactions with the environment.