Les activités de l'INTRIQ

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oct. 2, 2011

Meeting de l'INTRIQ (2 - 3 octobre 2011)

Location :

McGill University,

Rutherford Physics Building
 
3600 University Street
Montréal, Quebec H3A 2T8
 
Room 103, The "Bell Room"
 
 
sept. 16, 2010

Meeting de l'INTRIQ (16-17 septembre 2010)

Location

 

1 Rue Belvédère Sud
Sherbrooke

 

juin 7, 2010

Meeting de l'INTRIQ (7 - 8 juin 2010)

Location

Manoir St-Sauveur

 

246 Chemin du Lac Millette
St Sauveur J0R 1R3, QC, Canada

 

Axe 2 - Hardware

(- Cette section est en anglais pour permettre aux specialistes non-fracophones de la lire -)

From the first vacuum-tube-based digital devices to massively parallel supercomputers, classical information-processing hardware has both spurred and been driven by increasingly sophisticated software. For example, Graphics Processing Units (GPUs) were developed for graphical applications such as video games. Future quantum hardware must also evolve in close communication with its software counterpart. Moreover, just as conventional computing infrastructure combines magnetic memory with electronic circuits and fibre-optic relays, a quantum processor may require combining physical platforms with complementary characteristics: for example, superconducting qubits for fast processing, nuclear spins for long-term storage, and photons to carry information. Within INTRIQ, our members are pursuing a wide variety of physical systems. The diversity of expertise encourages collaborations linking different hardware platforms, and stimulates dialogue for application-driven device development.

Theme 2.1 - Electric charge
Transport and confinement of quantized electric charges presents a natural resource for quantum information science. Electrons flowing through a tunnel junction exhibit shot noise that enables generation of nonclassical electromagnetic signals: squeezing, photon pair generation, and even entanglement have all been experimentally demonstrated. Conversely, by confining electrons to quantum dots, their motional degrees of freedom are quantized, and it becomes possible to address individual electronic states. Such control over the electronic charge is closely interrelated with access to the electronic spin, while the charge itself couples strongly to optical and microwave photons.

Theme 2.2 - Spin
Isolated electronic or nuclear spins are among the most coherent systems, exhibiting quantum evolution on timescales that can stretch to seconds, minutes, or even hours. Fully exploiting that coherence requires developing methods to control spin states on fast timescales and, critically, learning to connect individual spin qubits into an interacting quantum processor. While direct spin-spin interactions present one scaling mechanism, a more versatile approach is to couple the spin to other, more mobile quantum degrees of freedom, such as optical or microwave photons or even phonons, that can mediate interactions with other spins or other qubits. Different types of spins and different confining mechanisms – such as quantum dots or crystal defects – offer complementary features, readily interacting with electric, magnetic, or even strain fields. In addition, coherent control over spin qubits can be exploited for near-term quantum technologies such as precision sensors.

Theme 2.3 - Composite and exotic electronic states
Superconducting qubits have risen to the forefront of quantum information processing platforms because their paired electronic states can be largely protected from noise by the superconducting gap, yet interact strongly with electromagnetic fields. Still more complex electronic states can give rise to anyons, exotic particles that naturally encode information in an inherently robust way. While cell phone communication requires error correction to protect the transmission from noise, the processor on a laptop does not: it is built from physical devices that are intrinsically robust. Similarly, anyons could feasibly store and process quantum information in an inherently robust way. Several candidates have been identified to fulfill this role: excitations in fractional quantum Hall fluids, edges excitations in nanowires, etc. While this research path is currently behind the other potential realizations of quantum devices, it could completely change the game for qubit technologies.

Theme 2.4 - Photons and phonons
An optical photon is a natural "flying qubit," capable of carrying quantum states encoded in its polarization, frequency, or timing through free space or over fibre-optic links. It is the natural medium for quantum communication, and development and construction of high-quality single photon sources is essential for many secure quantum cryptography protocols. Furthermore, by confining a photon to a resonator, it can live for long enough to interact strongly with any quantum system coupled to the cavity, for example a single spin. The same principles apply (with even greater enhancement) in the microwave regime, where INTRIQ researchers study superconducting elements coupled to microwave stripline resonators. Similarly, nanomechanical resonators enhance interactions between phonons and a variety of physical systems. Such resonator-based systems can be used to controllably create, manipulate, and transfer quantum states, even between qualitatively different quantum systems.

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