A New Method for Quick and Precise Measurement of Quantum States
January 11, 2017 | Vienna University of TechnologyEstimated reading time: 3 minutes
Nuclear spin tomography is an application in (human) medicine known from medical institutions. The patient absorbs and re-emits electromagnetic radiation in all directions in space. They are detected and 3D images or 2D slice images are reconstructed from that data. Set in the framework of a fundamental science laboratory, the patient is replaced by a quantum object and the electromagnetic radiation by quantum measurement. The result is a procedure referred to as quantum state tomography.
Reconstructing quantum states without post-processing
Quantum state tomography is the process of reconstructing – or more precisely completely characterizing – the quantum state of an object as it is emitted by its source, before a possible measurement or interaction with the environment takes place. This technique has become an essential tool in the emerging field of quantum technologies.
The theoretical framework of quantum state tomography dates back to the 1970s. Its experimental implementations are nowadays routinely carried out in a wide variety of quantum systems. The basic principle of quantum state tomography – as of is medical counterpart – is to repeatedly perform measurements from different spatial directions on the quantum systems in order to uniquely identify the system’s quantum state.
Nevertheless, for quantum state tomography a lot of computational post-processing of the measured data is required to deduce the initial quantum state from the observed measurement results – all together a high expenditure.
Consequently, in 2011 a novel, more direct tomographical method was established that makes it possible to determine the quantum state without the need for post-processing. However, that novel method had a major drawback: it uses minimally disturbing measurements, so called weak measurements, to determine the system’s quantum state.
The basic idea behind weak measurements is to gain very little information about the observed system, by keeping the disturbance, caused by the measurement process, (negligible) small. Usually, a measurement has a huge impact on a quantum system, causing typical quantum phenomena, such as entanglement or interference, to vanish irretrievably. Since the amount of information gained in this procedure is very small, the measurements have to be repeated multiple times – a huge disadvantage of this measurement procedure in practical applications.
A research team at the Institute of Atomic and Subatomic Physics of TU Wien headed by Stephan Sponar now managed to combine these two methods, benefitting from both.
Schematic illustration of an interferometric setup
“We were able to further develop the established method so that the need of weak measurements becomes obsolete. Thus, we were able to integrate usual, so-called strong measurements, in the direct measurement procedure of the quantum state. Consequently, it is possible to determine the quantum state with higher precision and accuracy in a much shorter time compared to the approach with weak measurements – a tremendous progress.”, explains Tobias Denkmayr the first author of the paper.
These results have now been published in the journal Physical Review Letters ("Experimental Demonstration of Direct Path State Characterization by Strongly Measuring Weak Values in a Matter-Wave Interferometer").
Page 1 of 2
Suggested Items
Lockheed Martin Successfully Transitions Long Range Discrimination Radar To The Missile Defense Agency
04/23/2024 | Lockheed MartinThe Long Range Discrimination Radar (LRDR) at Clear Space Force Station in Clear, Alaska, completed DD250 final acceptance and was officially handed over to the Missile Defense Agency in preparation for an Operational Capability Baseline (OCB) decision and final transition to the Warfighter. In addition, prior to this transition, the system has started Space Domain Awareness data collects for the United States Space Force.
Real Time with... IPC APEX EXPO 2024: AI Implementation at Omron
04/18/2024 | Real Time with...IPC APEX EXPOEditor Nolan Johnson and Omron Product Manager Nick Fieldhouse discuss the company's focus on AI implementation to enhance customer experience and results. They address programming challenges and how AI can help customers achieve better outcomes with less experience. Omron's AI is compatible with existing systems, facilitating easy upgrades.
Cadence Unveils Palladium Z3 and Protium X3 Systems
04/18/2024 | Cadence Design SystemsThe Palladium Z3 and Protium X3 systems offer increased capacity, and scale from job sizes of 16 million gates up to 48 billion gates, so the largest SoCs can be tested as a whole rather than just partial models, ensuring proper functionality and performance.
Australian Flow Batteries and The SCHMID Group Announce Groundbreaking Memorandum of Understanding
04/17/2024 | SCHMID GroupAustralian Flow Batteries Pty Ltd (AFB), a leader in innovative energy solutions and economical, safe, and reliable power storage, and SCHMID Energy Systems GmbH a company of the German SCHMID Group, a global technology leader with a rich history in delivering innovative solutions across multiple industries including Electronics, Renewables, and Energy Storage sectors, are thrilled to announce the signing of a Memorandum of Understanding (MoU)
Ansys Joins BAE Systems’ Mission Advantage Program to Advance Digital Engineering Across US Department of Defense
04/16/2024 | ANSYSAnsys announced it is working with BAE Systems, Inc., to accelerate the adoption of digital engineering and MBSE across the Department of Defense (DoD).