Welcome to the Institute for Quantum Computing
News
Waterloo researchers make a significant step towards reliably processing quantum information
Using laser light, researchers have developed the most robust method currently known to control individual qubits made of the chemical element barium. The ability to reliably control a qubit is an important achievement for realizing future functional quantum computers.
Researchers propose technique to detect microwave photons using point defects in diamond
Many experiments in quantum information processing rely on our ability to transmit, manipulate, or detect photons. In these applications, the wavelength of photons being detected can range from the infrared and visible light used in optical communication systems, to the microwave photons that superconducting quantum devices respond to. While a wide range of detectors are available for optical photons, detecting microwave photons is significantly more challenging due to the much lower energies of individual photons compared to the level of noise, including background light, in the world around us.
IQC Researchers receive funding in support of cutting-edge quantum projects
Six researchers from the Institute for Quantum Computing (IQC) have been awarded funding this week through the Natural Sciences and Engineering Research Council of Canada (NSERC) for their projects in quantum information science and technology.
Events
Impromptu Whiteboard Poster Session
Quantum Nano Centre (QNC) Room 1201, 200 University Avenue West, Waterloo, ON
This week’s student seminar will take place in the form of an impromptu whiteboard poster session, where attendees will be divided into groups and will discuss each other's current work using the whiteboard. This is to encourage students to talk about their work in progress, and practice communication skills by talking to non-experts (quantum is a big field!). As always, pizza will be provided for attendees after the seminar.
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Quantum gravity meets quantum cryptography
IQC Colloquium - Alex May, Perimeter Institute
Quantum Nano Centre (QNC) Room 0101 200 University Ave West, Waterloo Ontario
The subject of quantum gravity seeks to understand gravitational physics within the framework of quantum mechanics. Increasingly, tools from quantum information, complexity, and cryptography have been brought into this challenging area. Here, I describe a set of connections between quantum gravity, specifically the AdS/CFT correspondence, and a set of cryptographic primitives studied in information theoretic cryptography and position-verification. The cryptographic perspective provides new insights into how gravitational physics can be recorded into quantum mechanics, and led to new gravitational conjectures in AdS space. These conjectures were then proven gravitationally. Conversely, the gravitational perspective has suggested new relationships among these cryptographic primitives, and these relationships were then proven within quantum cryptography. I comment on some directions this cryptography-gravity relationship may lead in the future.
Fully-quantum learning: Comparison of unknown unitary channels with multiple uses
IQC Colloquium - Mio Murao, The University of Tokyo
Quantum Nano Centre (QNC) Room 0101 200 University Ave West, Waterloo Ontario
Please note start time 3:00 PM
Efficiently learning properties of unknown quantum objects is a fundamental task in quantum mechanics and quantum information. When there are two unknown quantum objects, and if we want to learn just the relationship between the objects, a method to directly compare the two objects without identifying their descriptions is preferable, especially when the number of available copies of each target object is limited. In this work, we investigate the comparison of unknown unitary channels with multiple uses of the unitary channels based on the quantum tester formalism. We obtain the optimal minimum-error strategy and the optimal unambiguous strategy of unitary comparison of two unknown d-dimensional unitary channels when the number of uses of the channels satisfies a certain condition. These optimal strategies are implemented by parallel uses of the unitary channels, even though all sequential and adaptive strategies implementable by the quantum circuit model are considered. When the number of the smaller uses of the unitary channels is fixed, the optimal averaged success probability is achieved by a certain number of uses of the other channel. This feature contrasts with the case of pure-state comparison, where adding more copies of the unknown pure states always improves the optimal averaged success probability. It highlights the difference between corresponding tasks for states and channels, which has been previously shown for quantum discrimination tasks.
Reference: Y. Hashimoto, A. Soeda and M. Murao, Comparison of unknown unitary channels with multiple uses, arXiv:2208.12519