Quantum State Interferography

Why in NEWS?

• Scientists from Raman Research Institute(RRI), an autonomous institute under the Department of Science & Technology, Government. 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’.

About

• New ways to manipulate quantum states can be harnessed for computing, communication, and metrology.
• It can help make such manipulations simpler so that several crucial operations in quantum technologies become less cumbersome.
• This work, partially supported by the QuEST network programme of the DST (Department of Science & Technology), has been accepted for publication in the journal Physical Review Letters.

Current System and New Development

• 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.

Pranab Mukherjee Obituary

Why in NEWS?

• Respected Pranab Mukherjee, former President of India and Bharat Ratna, died on 31 st August, 2020 at a hospital in New Delhi. He was 84.

Cause

• Before undergoing brain surgery in recent weeks, Mr. Mukherjee announced on Twitter that he had also tested positive for the coronavirus. He was later put on a ventilator and slipped into a coma, according to doctors who were treating him at a military hospital.

About Pranab Mukherjee

• He became the 13th President of India in 2012, he held the presidential post from 2012 to 2017
• He became member of Parliament for the first time in 1969 when Indira Gandhi nominated him to the Rajya Sabha in 1969.
• He later served as Finance Minister (1982-84), commerce minister (1993-1995), as external affairs minister (1995-96) and as defence minister in the Manmohan Singh government (2004-2006).
• He was also appointed as leader of Rajya Sabha in 1980 and in Lok Sabha in 2004 and later in 2009.
• Pranab Mukherjee was conferred the Bharat Ratna award in 2019.