Why saying Quantum Mechanics is pillar of QFT?

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Quantum Mechanics (QM) is considered a pillar of Quantum Field Theory (QFT) because QFT extends QM principles to fields rather than particles. The operators in QFT obey equations like the Dirac or Klein-Gordon equations, which are foundational in QM. While fields in QFT can be viewed as analogous to wave functions in QM, the two concepts differ in their application and interpretation. QFT can be understood more clearly through the Heisenberg picture, emphasizing its connection to QM. Overall, QFT represents the quantum mechanics of large local systems, revealing new physics through the interaction of multiple quantum degrees of freedom.
ndung200790
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Please teach me this:
Why they say QM is a pillar of QFT?Is it correct it is because of the operator of field obeys the Dirac or Klein-Gordon equation of QM?Is the value of fields(not operator of fields) being the wave function in QM?I do not understand why we can consider QFT including QM.
Thank you very much for your kind helping.
 
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If we replace the wave function notion by value of field notion,it seem that the formation of Quantum Mechanics is unchanged?(if we consider the value of field is different from wave function)
 
QM just means a theory that can be put in the form of the QM axioms eg. http://arxiv.org/abs/0707.2832 .

The axioms of QFT have such a form.

Usually it is easiest to see that QFT is a form of QM by using the Heisenberg picture rather than the Schroedinger picture of QM.
 
Ask yourself <What is Quantum Field Theory?>. It might help you by reading the article by Steven Weinberg which can be found on the arxiv.org. As soon as you get an idea about what QFT is, you shall immediately see its connection with the theory of Quantum Mechanics.
 
QFT is really "just" the quantum mechanics of large local systems. Nevertheless, much new physics emerges when there are many interacting quantum degrees of freedom.
 
Time reversal invariant Hamiltonians must satisfy ##[H,\Theta]=0## where ##\Theta## is time reversal operator. However, in some texts (for example see Many-body Quantum Theory in Condensed Matter Physics an introduction, HENRIK BRUUS and KARSTEN FLENSBERG, Corrected version: 14 January 2016, section 7.1.4) the time reversal invariant condition is introduced as ##H=H^*##. How these two conditions are identical?

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