Difference between revisions of "Hilbert Space"

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(Created page with "==Full Title== ==Context== ⋆ In quantum mechanics the state of a physical system is represented by a vector in a Hilbert space: a complex vector space with an inner produc...")
 
(Context)
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==Context==
 
==Context==
 
+
* In quantum mechanics the state of a physical system is represented by a vector in a Hilbert space: a
In quantum mechanics the state of a physical system is represented by a vector in a Hilbert space: a
 
 
complex vector space with an inner product.
 
complex vector space with an inner product.
The term “Hilbert space” is often reserved for an infinite-dimensional inner product space having the
+
* The term “Hilbert space” is often reserved for an infinite-dimensional inner product space having the
 
property that it is complete or closed. However, the term is often used nowadays, as in these notes, in a way
 
property that it is complete or closed. However, the term is often used nowadays, as in these notes, in a way
 
that includes finite-dimensional spaces, which automatically satisfy the condition of completeness.
 
that includes finite-dimensional spaces, which automatically satisfy the condition of completeness.
1
+
* We will use Dirac notation in which the vectors in the space are denoted by |v>, called a ket, where v
We will use Dirac notation in which the vectors in the space are denoted by |vi, called a ket, where v
 
 
is some symbol which identifies the vector.
 
is some symbol which identifies the vector.
One could equally well use something like ~v or v. A multiple of a vector by a complex number c is written
+
* One could equally well use something like '''v'''. A multiple of a vector by a complex number c is written
as c|vi—think of it as analogous to c~v of cv.
+
as c|v> -think of it as analogous to c'''v'''.
In Dirac notation the inner product of the vectors |vi with |wi is written hv|wi. This resembles the
+
* In Dirac notation the inner product of the vectors |v> with |w> is written <v|w>. This resembles the
 
ordinary dot product ~v · ~w except that one takes a complex conjugate of the vector on the left, thus think of
 
ordinary dot product ~v · ~w except that one takes a complex conjugate of the vector on the left, thus think of
~v∗
+
~v∗· ~w.
· ~w.
 
  
 
==References==
 
==References==
  
 
[[Category: Physics]]
 
[[Category: Physics]]

Revision as of 07:46, 27 April 2023

Full Title

Context

  • In quantum mechanics the state of a physical system is represented by a vector in a Hilbert space: a

complex vector space with an inner product.

  • The term “Hilbert space” is often reserved for an infinite-dimensional inner product space having the

property that it is complete or closed. However, the term is often used nowadays, as in these notes, in a way that includes finite-dimensional spaces, which automatically satisfy the condition of completeness.

  • We will use Dirac notation in which the vectors in the space are denoted by |v>, called a ket, where v

is some symbol which identifies the vector.

  • One could equally well use something like v. A multiple of a vector by a complex number c is written

as c|v> -think of it as analogous to cv.

  • In Dirac notation the inner product of the vectors |v> with |w> is written <v|w>. This resembles the

ordinary dot product ~v · ~w except that one takes a complex conjugate of the vector on the left, thus think of ~v∗· ~w.

References