Weak Measurement and Quantum Correlation Arun Kumar Pati Quantum Information and Computation Group Harish-Chandra Research Institute Allahabad 211 019, India Arun Kumar Pati (HRI) 1 / 24 Outlines Quantum World Weak Measurements Quantum correlation Super Quantum Discord Quantum-Classical Boundary Conclusions Arun Kumar Pati (HRI) 2 / 24 Outlines Quantum World Weak Measurements Quantum correlation Super Quantum Discord Quantum-Classical Boundary Conclusions Arun Kumar Pati (HRI) 2 / 24 Outlines Quantum World Weak Measurements Quantum correlation Super Quantum Discord Quantum-Classical Boundary Conclusions Arun Kumar Pati (HRI) 2 / 24 Outlines Quantum World Weak Measurements Quantum correlation Super Quantum Discord Quantum-Classical Boundary Conclusions Arun Kumar Pati (HRI) 2 / 24 Outlines Quantum World Weak Measurements Quantum correlation Super Quantum Discord Quantum-Classical Boundary Conclusions Arun Kumar Pati (HRI) 2 / 24 Outlines Quantum World Weak Measurements Quantum correlation Super Quantum Discord Quantum-Classical Boundary Conclusions Arun Kumar Pati (HRI) 2 / 24 Outlines Quantum World Weak Measurements Quantum correlation Super Quantum Discord Quantum-Classical Boundary Conclusions Arun Kumar Pati (HRI) 2 / 24 Quantum World Even after more than 100 years, quantum theory still continues to surprise us.... Linear superposition: A quantum system can remain simultaneously in all possible allowed states. Entanglement: Two quantum systems can be in a strongly correlated state even if they are far apart (Einstein, Schrodinger).¨ Non-locality: Correlations in entangled state cannot be explained by local-realistic theory (Bell). Quantum Measurement : State vector collapses in a probabilistic way to one of the eigenstate and coherence is lost. Arun Kumar Pati (HRI) 3 / 24 Quantum World Even after more than 100 years, quantum theory still continues to surprise us.... Linear superposition: A quantum system can remain simultaneously in all possible allowed states. Entanglement: Two quantum systems can be in a strongly correlated state even if they are far apart (Einstein, Schrodinger).¨ Non-locality: Correlations in entangled state cannot be explained by local-realistic theory (Bell). Quantum Measurement : State vector collapses in a probabilistic way to one of the eigenstate and coherence is lost. Arun Kumar Pati (HRI) 3 / 24 Quantum World Even after more than 100 years, quantum theory still continues to surprise us.... Linear superposition: A quantum system can remain simultaneously in all possible allowed states. Entanglement: Two quantum systems can be in a strongly correlated state even if they are far apart (Einstein, Schrodinger).¨ Non-locality: Correlations in entangled state cannot be explained by local-realistic theory (Bell). Quantum Measurement : State vector collapses in a probabilistic way to one of the eigenstate and coherence is lost. Arun Kumar Pati (HRI) 3 / 24 Quantum World Even after more than 100 years, quantum theory still continues to surprise us.... Linear superposition: A quantum system can remain simultaneously in all possible allowed states. Entanglement: Two quantum systems can be in a strongly correlated state even if they are far apart (Einstein, Schrodinger).¨ Non-locality: Correlations in entangled state cannot be explained by local-realistic theory (Bell). Quantum Measurement : State vector collapses in a probabilistic way to one of the eigenstate and coherence is lost. Arun Kumar Pati (HRI) 3 / 24 Quantum World Even after more than 100 years, quantum theory still continues to surprise us.... Linear superposition: A quantum system can remain simultaneously in all possible allowed states. Entanglement: Two quantum systems can be in a strongly correlated state even if they are far apart (Einstein, Schrodinger).¨ Non-locality: Correlations in entangled state cannot be explained by local-realistic theory (Bell). Quantum Measurement : State vector collapses in a probabilistic way to one of the eigenstate and coherence is lost. Arun Kumar Pati (HRI) 3 / 24 Quantum World Even after more than 100 years, quantum theory still continues to surprise us.... Linear superposition: A quantum system can remain simultaneously in all possible allowed states. Entanglement: Two quantum systems can be in a strongly correlated state even if they are far apart (Einstein, Schrodinger).¨ Non-locality: Correlations in entangled state cannot be explained by local-realistic theory (Bell). Quantum Measurement : State vector collapses in a probabilistic way to one of the eigenstate and coherence is lost. Arun Kumar Pati (HRI) 3 / 24 Quantum Entanglement Schrodinger¨ (1935): “When two systems ... enter into temporary physical interaction ... and when after a time of mutual influence the systems separate again, then they can no longer be described in the same way as before, viz. by endowing each of them with a representative of its own. I would not call that one but rather the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of thought. By the interaction the two representatives (the quantum states) have become entangled. Arun Kumar Pati (HRI) 4 / 24 Quantum Entanglement Schrodinger¨ (1935): “When two systems ... enter into temporary physical interaction ... and when after a time of mutual influence the systems separate again, then they can no longer be described in the same way as before, viz. by endowing each of them with a representative of its own. I would not call that one but rather the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of thought. By the interaction the two representatives (the quantum states) have become entangled. Arun Kumar Pati (HRI) 4 / 24 Quantum Entanglement Schrodinger¨ (1935): “When two systems ... enter into temporary physical interaction ... and when after a time of mutual influence the systems separate again, then they can no longer be described in the same way as before, viz. by endowing each of them with a representative of its own. I would not call that one but rather the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of thought. By the interaction the two representatives (the quantum states) have become entangled. Arun Kumar Pati (HRI) 4 / 24 Quantum Information These are resources which can be used to design quantum computer, quantum information processor, quantum communication and quantum information technology. Merging of quantum mechanics and information theory —quantum information science – with important developments like quantum cryptography (Ekert 1991), quantum teleportation (Bennett et al 1993), remote state preparation (Pati 1999) and many more. Quantum Correlations play important role. Entanglement and beyond (Quantum Discord) for composite systems. Arun Kumar Pati (HRI) 5 / 24 Quantum Information These are resources which can be used to design quantum computer, quantum information processor, quantum communication and quantum information technology. Merging of quantum mechanics and information theory —quantum information science – with important developments like quantum cryptography (Ekert 1991), quantum teleportation (Bennett et al 1993), remote state preparation (Pati 1999) and many more. Quantum Correlations play important role. Entanglement and beyond (Quantum Discord) for composite systems. Arun Kumar Pati (HRI) 5 / 24 Quantum Information These are resources which can be used to design quantum computer, quantum information processor, quantum communication and quantum information technology. Merging of quantum mechanics and information theory —quantum information science – with important developments like quantum cryptography (Ekert 1991), quantum teleportation (Bennett et al 1993), remote state preparation (Pati 1999) and many more. Quantum Correlations play important role. Entanglement and beyond (Quantum Discord) for composite systems. Arun Kumar Pati (HRI) 5 / 24 Quantum Information These are resources which can be used to design quantum computer, quantum information processor, quantum communication and quantum information technology. Merging of quantum mechanics and information theory —quantum information science – with important developments like quantum cryptography (Ekert 1991), quantum teleportation (Bennett et al 1993), remote state preparation (Pati 1999) and many more. Quantum Correlations play important role. Entanglement and beyond (Quantum Discord) for composite systems. Arun Kumar Pati (HRI) 5 / 24 Quantum Information These are resources which can be used to design quantum computer, quantum information processor, quantum communication and quantum information technology. Merging of quantum mechanics and information theory —quantum information science – with important developments like quantum cryptography (Ekert 1991), quantum teleportation (Bennett et al 1993), remote state preparation (Pati 1999) and many more. Quantum Correlations play important role. Entanglement and beyond (Quantum Discord) for composite systems. Arun Kumar Pati (HRI) 5 / 24 Quantum Information These are resources which can be used to design quantum computer, quantum information processor, quantum communication and quantum information technology. Merging of quantum mechanics and information theory —quantum information science – with important developments like quantum cryptography (Ekert 1991), quantum teleportation (Bennett et al 1993), remote state preparation (Pati 1999) and many more. Quantum Correlations