31-Aug-2020: RRI Scientists find a new way for quantum state estimation that can make crucial quantum operations simpler
Scientists experimenting with new ways to manipulate quantum states so that they can be harnessed for computing, communication, and metrology, has found a novel way to characterise and estimate such states. This method of characterisation called Quantum State Interferography, can help make such manipulations simpler so that several crucial operations in quantum technologies become less cumbersome.
Scientists from Raman Research Institute, an autonomous institute under the Department of Science & Technology, Govt. of India, have found a new way of inferring the state of a system (both two-dimensional qubits, the simplest quantum system as well as higher-dimensional “qubits”) from an interference pattern, which they term ‘Quantum State Interferography’. This work, partially supported by the QuEST network programme of the DST, has been accepted for publication in the journal Physical Review Letters.
The determination of an unknown quantum state is usually done by a method known as Quantum State Tomography (QST). This involves measuring projection of the quantum state on various directions in state space and reconstructing the quantum state from the information obtained. However, in particular, scenarios where the dimensions are large, the operations needed to perform tomography increase quadratically. The experimental settings often need to be changed many times, thus making the process very cumbersome.
The RRI team showed that without changing any settings in the experimental setup, it is possible to infer the unknown quantum state of a higher dimensional system. The setup requires only two interferometers from which many interferograms can be obtained to reconstruct the state. This provides a ‘black box’ approach to quantum state estimation -- between the incidence of the photon and extraction of state information, conditions within the set-up are not changed, thus providing a true single-shot estimation of the quantum state.
A qubit is a 2-dimensional quantum system and requires usually 2 complex numbers to be determined towards state estimation. However, various constraints and physical assumptions leave only two real numbers, finally to be determined. Instead of finding these two real numbers from various projections, in this work, they were determined from the intensity and phase shift of the interference pattern. Also, when many such quantum states are incoherently mixed, the amount of mixedness can be determined from the visibility of the interference pattern. This can be used to characterize the state of a two-particle system, which in turn can be used to quantify entanglement, also in a single-shot method. This idea can be further extended to find parameters describing higher-dimensional quantum states from a set of interference patterns.
This work gives a single-shot black-box approach to quantum state estimation as well as quantifying quantum entanglement. Manipulation of quantum states is the most crucial operation in any quantum technology protocol, be it quantum computing, quantum communication, or quantum metrology. Similarly, quantum entanglement is a ubiquitous resource in quantum technology. The new technique for quantum state estimation developed and experimentally demonstrated by Urbasi Sinha and her group members at the Quantum Information and Computing Lab at RRI is a handy and effective tool in comparison to conventional techniques with a tremendous scaling gain involving the use of interferometry. Theoretical support for this development was provided by a collaborator from HRI. Moreover, the work also indicates how this technique could lead to miniaturised devices in the long run, which could be used for quantum state estimation at a commercial scale.
3-Dec-2019: CSIR-IICT Nuclear Magnetic Resonance test facility gets US FDA certification
The Nuclear Magnetic Resonance (NMR) test facility at the CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad has passed the US Food and Drug Administration (USFDA) inspection with “no observations”.
The NMR spectroscopy is an important technique for structural characterization of pharmaceutical and other chemical molecules.
The USFDA inspected the NMR facility during August 21-22 and found the facility in an acceptable state of compliance with regard to Current Good Manufacturing Practice (CGMP). Accordingly it classified the facility as “no action initiated (NAI)”.
NMR laboratory, an NABL accredited facility is one of the country's largest facilities, equipped with nine state-of-the art high field NMR spectrometers, and the USFDA's clearance has added further impetus to the wide range of quality analytical R&D services for Active Pharmaceutical Ingredients (API).
13-Dec-2019: Development of New System for Measurement of Weight
The prototype of one kilogram(NPK-57) is already available in India and placed at the National Physical Laboratory, New Delhi as per the provisions made under the Legal Metrology (National Standards) Rules, 2011.
The new definition of kilogram which has come into effect from May, 2019 and few countries have developed the system of realisation of unit of mass ‘kg’. The previous definition of kilogram was based on the mass of the international prototype ‘kilogram’ which is an artefact, however, the new definition is based on physical constant of nature. The change in the definition of kilogram will not have any implication in daily life in weighing of pharma and precious metals.
21-May-2019: India adopts new definition of kilogram
The CSIR-NPL, which is India’s official reference keeper of units of measurements has released a set of recommendations requiring that school textbooks, engineering-education books, and course curriculum update the definition of the kilogram.
The institute is also in the process of making its own ‘Kibble Balance’, a device that was used to measure the Planck Constant and thereby reboot the kilogram.
Scientists, last year, have changed the way the kilogram is defined. The decision was made at the General Conference on Weights and Measures. The new definitions came into force on 20 May 2019.
Currently, it is defined by the weight of a platinum-based ingot called “Le Grand K” which is locked away in a safe in Paris. Le Grand K has been at the forefront of the international system of measuring weights since 1889. Several close replicas were made and distributed around the globe. But the master kilogram and its copies were seen to change – ever so slightly – as they deteriorated.
In a world where accurate measurement is now critical in many areas, such as in drug development, nanotechnology and precision engineering – those responsible for maintaining the international system had no option but to move beyond Le Grand K to a more robust definition.
The fluctuation is about 50 parts in a billion, less than the weight of a single eyelash. But although it is tiny, the change can have important consequences.
Electromagnets generate a force. Scrap-yards use them on cranes to lift and move large metal objects, such as old cars. The pull of the electromagnet, the force it exerts, is directly related to the amount of electrical current going through its coils. There is, therefore, a direct relationship between electricity and weight.
So, in principle, scientists can define a kilogram, or any other weight, in terms of the amount of electricity needed to counteract the weight (gravitational force acting on a mass).
There is a quantity that relates weight to electrical current, called Planck’s constant – named after the German physicist Max Planck and denoted by the symbol h. But h is an incredibly small number and to measure it, the research scientist Dr Bryan Kibble built a super-accurate set of scales. The Kibble balance, as it has become known, has an electromagnet that pulls down on one side of the scales and a weight – say, a kilogram – on the other. The electrical current going through the electromagnet is increased until the two sides are perfectly balanced. By measuring the current running through the electromagnet to incredible precision, the researchers are able to calculate h to an accuracy of 0.000001%. This breakthrough has paved the way for Le Grand K to be deposed by “die kleine h”.
5-Feb-2019: New Scientific Standard of Kg
The prototype of one kilogram (NPK-57) is already available in India and placed at National Physical Laboratory, New Delhi as per the provisions made under the Legal Metrology (National Standards) Rules, 2011. There is no such proposal at present before the Government to achieve the new prototype of kilogram through physical constants.
The previous definition of kilogram was based on the mass of the international prototype ‘kilogram’ which is an artefact, however, the new definition is based on physical constants of nature. The change is in the definition of kilogram and will not have any practical implications.
16-Nov-2018: Kilogram gets a new definition
Scientists have changed the way the kilogram is defined. Currently, it is defined by the weight of a platinum-based ingot called "Le Grand K" which is locked away in a safe in Paris. On Friday, researchers meeting in Versailles voted to get rid of it in favour of defining a kilogram in terms of an electric current. The decision was made at the General Conference on Weights and Measures.
Le Grand K has been at the forefront of the international system of measuring weights since 1889. Several close replicas were made and distributed around the globe. But the master kilogram and its copies were seen to change - ever so slightly - as they deteriorated.
In a world where accurate measurement is now critical in many areas, such as in drug development, nanotechnology and precision engineering - those responsible for maintaining the international system had no option but to move beyond Le Grand K to a more robust definition.
How wrong is Le Grand K?
The fluctuation is about 50 parts in a billion, less than the weight of a single eyelash. But although it is tiny, the change can have important consequences. Coming in is an electrical measurement which Dr Stuart Davidson, head of mass metrology at NPL, says is more stable, more accurate and more egalitarian.
How does the new system work?
Electromagnets generate a force. The pull of the electromagnet, the force it exerts, is directly related to the amount of electrical current going through its coils. There is, therefore, a direct relationship between electricity and weight. So, in principle, scientists can define a kilogram, or any other weight, in terms of the amount of electricity needed to counteract the weight (gravitational force acting on a mass).
There's already a quantity that relates weight to electrical current, called Planck's constant - named after the German physicist Max Planck and denoted by the symbol h. But h is an incredibly small number and to measure it, the research scientist Dr Bryan Kibble built a super-accurate set of scales. The Kibble balance, as it has become known, has an electromagnet that pulls down on one side of the scales and a weight - say, a kilogram - on the other.
The electrical current going through the electromagnet is increased until the two sides are perfectly balanced. By measuring the current running through the electromagnet to incredible precision, the researchers are able to calculate h to an accuracy of 0.000001%. This breakthrough has paved the way for Le Grand K to be deposed by "die kleine h".
What are the advantages of the new system?
Every few decades, all the replica kilograms in the world had to be checked against Le Grand K. The new system, now that it's been adopted, will allow anyone with a Kibble balance to check their weights anytime and anywhere.