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Quantum Enabling System Technologies (QuEST) Group

Koç University

Ongoing Projects

 Since quantum technologies can operate at low temperatures, precise monitoring of their temperatures is required. Measuring low temperatures precisely is a difficult and open problem. Quantum thermometry seeks a solution to this problem, benefiting from developments in the fields of quantum thermodynamics and quantum metrology. It is aimed at benefiting from quantum thermometers for precise temperature measurements. Beyond quantum technologies, it is expected that existing industries, such as biomedicine and materials technologies, will also benefit from the results of quantum thermometry. In our project, we aim to systematically examine quantum thermometers, determine their basic limits in temperature measurements, and develop them with features such as quantum entanglement. 

Quantum sensors need to be more sensitive than their classical counterparts, and they need to be more compact, fast, and give precise results with a small amount of data to be used more in practical life. For small quantum sensors to demonstrate quantum advantages, many qubits, and the material to be measured must interact in a compact space. The aim of our project is to show the finite system effects such as surface proximity, qubit number, and sensor geometry on the metrological performances such as sensitivity, speed, and data economy of quantum sensors consisting of qubit groups close to the surface and to propose the optimum designs of practical quantum sensors according to them. It is also one of the aims of the project to use our findings to propose optimum quantum measurement systems in application areas such as biosensing, thermometry, and magnetometry by considering different modern quantum sensor systems, from topological networks with superconducting optomechanical quantum diamond nitrogen-vacancy defects in the hydrogel.

Past Projects

Quantum optomechanics explores the interaction between radiation and mechanical degrees of freedom of a system by using quantum mechanical models of the electromagnetic field and the mechanical matter. It could play a significant role in future space missions such as using massive mechanical mirrors for high-mass matter-wave interferometry to test foundations of physics or for controlling quantum noise for gravitational wave detection. These are challenging to implement due to special requirements that should be met depending on the orbit, radiation, temperature gradients, mass and size restrictions, long-term stability, extreme forces during the launch phase, etc. A central problem in such space missions is efficient manipulation of heat transfer, in addition to receiving and rejecting heat. Another heat related major problem is to cool scientific instruments on board a spacecraft. This is achieved by either passively, using background thermal radiation in deep space, or actively, which is not preferred due to requirement of massive cryogenic components such as Helium tanks. Small, compact, and efficient cooling systems are highly sought for space applications. Existing studies are mainly instrument-specific and limited to classical models. Rapidly developing modern field of quantum thermodynamics promises quantum refrigerators with few qubits as well as highly efficient quantum heat transfer modules which can offer enabling technologies for space missions such as quantum-engineered functionalized interface surfaces and quantum heat machines.

Funding: EU-COST Action (CA15220) and TUBITAK (116F303)

Thermodynamics is the science of heat engines, or more fundamentally, science of energy, focusing on the interplay between heat and work. It is developed to deal with macroscopic systems, yet there is recent interest to built engines in microscopic limits. It is therefore necessary to examine thermodynamics in quantum regime. Exploration of quantum analogs of classical heat engines can be traced back to the recognition of maser as an Otto engine in 50s. Since then, quantum dots, trapped ions, spin systems, atomic condensates, optical cavities, quantum Hall systems, optomechanical resonators, and relativistic particles are considered as working substances for quantum heat engines (QHEs). Profound quantum effects emerge when quantum heat reservoirs are included. If quantum heat bath has quantum coherence, entanglement, or squeezing, QHE can surpass the Carnot bound. Observation of quantum advantages is challenged due to decoherence. However, quantum coherence is argued to survive in ambient temperatures in some biological processes, such as photosynthesis, being responsible for the ballistic transfer of energy. Information feedback from the environment could help to maintain coherence in these processes. Such an environment has a memory and called a non-Markovian reservoir. It is suggested for longevity of quantum memories, a crucial ingredient for quantum communication and quantum computation. Despite the analogies between QHEs and quantum information devices, there are only a few studies of non-Markovian reservoirs for QHEs. Our fundamental purpose is to establish mechanical equivalent of non-Markovian resources. Our practical purpose is to propose an optimum QHE that can use non-Markovian resources with capabilities surpassing classical counterparts.

Experimental evidences of long-lasting quantum coherence in the excitation energy transfer (EET) through photosynthetic pigment-protein complexes (such as FMO complex) have been reported since 2008 [1-4]. These observations together with the some other unexpected quantum coherence related observations (magneto-reception in birds and olfactory sense) in biological systems [5] led to a quest for novel theoretical explanations of these observations. It is argued that existence of quantum coherent superposition of excitons in the EET can bring an explanation [5] [6]. However, in large and noisy systems, coherence cannot live long. Yet this still can be explained by an interplay of non-Markovianity, open system quantum dynamics, and quantum coherence [7]. In our project, we are aiming to approach these observations in natural photosynthesis by realistic energy transfer models taking into account memory effects in the environment and quantum coherence; and then by following a bio-mimetic approach, we will propose efficient artificial photosynthesis systems. Intriguingly, our results could have broader scope as it is related to the interplay of quantum information and energy in non-Markovian open systems dynamics and could impact information storage and manipulation ways for quantum communication and computations.



Our objective in this multinational project is to investigate if quantum physics can help to enhance the capabilities of energy storage and processing devices. We have recently reported that superradiance can be used as a “superwork” harvesting scheme that can lead to quadratic increase in the work output of a photonic Otto engine with the number of atoms powering the device [1]. We identified the physics behind the enhancement as a catalytic effect of quantum coherence. Our photonic quantum engine designs are inspired from light harvesting photosynthetic systems which can be relevant to “quantum photovoltaics” and “quantum biology” as well. In addition to photonic devices we consider atomic and molecular clusters, spin systems, including NMR, optomechanical and superconducting circuit QED systems for implementations of our ideas. We collaborate with Prof. Christopher Wilson group of IQC at University of Waterloo for experimental realizations. We have recently proposed a superconducting quantum piston engine [2]. This project is funded by a University Research Agreement between Koç University and Lockheed-Martin Chief Scientist’s Office.

We are also a member of atomQT action.



Quantum Vision Project

In quantum vision project, our objective is to utilize the tools of quantum information theory and quantum metrology in order to unravel the secrets of visual system and pave the way for new technologies. In this project we will analyze the feasibility quantum states of light for high precision retinal measurements. The advantages of quantum states of light over classical light for probing the retina and visual system will be evaluated. By proposing novel experiments and devices we will make pioneering contributions to quantum biometry and ophtalmology. For more information you can visit the website for Quantum Vision Project.