求基态量子谐振子的⟨x⟩、⟨x2⟩、⟨px⟩和⟨px2⟩,然后确定位置和动量的测不准量。位置和动量的测不准量之积是否与海森堡测不准原理一致?
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| 海森堡测不准原理  
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基态量子谐振子的波函数为
 利用此波函数,可以计算平均位置和位置平方的平均值。
 利用此波函数,可以计算平均位置和位置平方的平均值。
平均位置
 
 
 
 
  
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| 使用  |  
 
 
 
 
 
 
![{\displaystyle \qquad \qquad \qquad \qquad \quad \ ={\Bigl (}{\frac {\alpha }{\pi }}{\Bigr )}^{\frac {1}{2}}{\biggl [}{\frac {-1}{2\alpha }}\cdot e^{-\alpha x^{2}}{\biggl ]}_{-\infty }^{\infty }}](https://wikimedia.org/api/rest_v1/media/math/render/svg/ac9fb1c65a597f89866342c2e242e7711e1d9a29) 
 
![{\displaystyle \qquad \qquad \qquad \qquad \quad \ ={\Bigl (}{\frac {\alpha }{\pi }}{\Bigr )}^{\frac {1}{2}}{\biggl [}{\frac {-1}{2\alpha }}(0)-{\frac {1}{2\alpha }}(0){\biggl ]}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/4623aa0982f3eb60f69e1479d2c8c77c3eed8123) 
 
位置的平均平方
 
 
 
                  
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| 使用  |  
 
 
 
 
 
 
 
 
 
 
![{\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\Bigl (}{\frac {\alpha }{\pi }}{\Bigr )}^{\frac {1}{2}}{\Biggl [}{\frac {{\sqrt {\pi }}{\text{erf}}({\sqrt {\alpha }}x)}{4\alpha ^{\frac {3}{2}}}}\ -\ {\frac {xe^{-\alpha x^{2}}}{2\alpha }}{\Biggl ]}_{-\infty }^{\infty }}](https://wikimedia.org/api/rest_v1/media/math/render/svg/cb23fc1dd04638c74e2de7541a12aece057d2d4d) 
![{\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\Bigl (}{\frac {\alpha }{\pi }}{\Bigr )}^{\frac {1}{2}}{\Biggl [}{\frac {\sqrt {\pi }}{4}}{\frac {{\text{erf}}({\sqrt {\alpha }}\ \infty )}{\alpha ^{\frac {3}{2}}}}\ -\ \lim _{x\to \infty }{\frac {xe^{-\alpha x^{2}}}{2\alpha }}{\Biggl ]}\ -\ {\Biggl [}{\frac {\sqrt {\pi }}{4}}{\frac {{\text{erf}}({\sqrt {\alpha }}-\infty )}{\alpha ^{\frac {3}{2}}}}\ -\ \lim _{x\to -\infty }{\frac {xe^{-\alpha x^{2}}}{2\alpha }}{\Biggl ]}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/04e997cc1fe15cf3b2cfc94d2736f1de8080f542) 
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| 使用  以及  |  
 
 
 
 
 
 
 
 
 
 
![{\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\Bigl (}{\frac {\alpha }{\pi }}{\Bigr )}^{\frac {1}{2}}\ {\frac {\sqrt {\pi }}{4}}\ {\frac {1}{\alpha ^{\frac {3}{2}}}}\ {\biggl [}1-(-1){\biggl ]}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/161d24f11477ac620d924af9c081675de7ac873f) 
                  
![{\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {\sqrt {\alpha }}{\sqrt {\pi }}}\ {\frac {\sqrt {\pi }}{4}}\ {\frac {1}{\alpha ^{\frac {3}{2}}}}\ {\bigl [}2{\bigl ]}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/833fad4fa713f013750145ea0e55fe097c3e2d67) 
 
位置的不确定性

 
 
动量的平均值
 
 
 
 
 
    
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| 使用  |  
 
 
 
 
 
 
 
 
 
![{\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {-\alpha ^{\frac {3}{2}}}{\sqrt {\pi }}}-i\hbar \ {\biggl [}{\frac {1}{2\alpha }}\ e^{-2\alpha x^{2}}{\biggl ]}_{-\infty }^{\infty }}](https://wikimedia.org/api/rest_v1/media/math/render/svg/53b31b9136a4ed2fd06e9416ecadf14fc3b519a5) 
![{\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {-\alpha ^{\frac {3}{2}}}{\sqrt {\pi }}}-i\hbar {\biggl [}{\frac {1}{2\alpha }}(0)-{\frac {1}{2\alpha }}(0){\biggl ]}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/ea3d6d135db173403156ee6e3bbad8ffc2f4da58) 
 
动量的平均平方
 
           =   (     α π      )     1 2    ( − 1 )  ℏ  2    ∫  − ∞   ∞    e    − α  x  2    2      (     ∂  ∂ x      )       (   − α x  e    − α  x  2    2      )     d x   {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\Bigl (}{\frac {\alpha }{\pi }}{\Bigr )}^{\frac {1}{2}}(-1)\hbar ^{2}\int _{-\infty }^{\infty }e^{\frac {-\alpha x^{2}}{2}}{\Biggl (}{\frac {\partial }{\partial x}}{\Biggr )}\ {\biggl (}-\alpha xe^{\frac {-\alpha x^{2}}{2}}{\biggl )}\ dx}   
           = α   (     α π      )     1 2     ℏ  2    ∫  − ∞   ∞    e    − α  x  2    2      (    e    − α  x  2    2    + α  x  2    e    − 2 α  x  2    2      )     d x   {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad =\alpha {\Bigl (}{\frac {\alpha }{\pi }}{\Bigr )}^{\frac {1}{2}}\hbar ^{2}\int _{-\infty }^{\infty }e^{\frac {-\alpha x^{2}}{2}}{\biggl (}e^{\frac {-\alpha x^{2}}{2}}+\alpha x^{2}e^{\frac {-2\alpha x^{2}}{2}}{\biggl )}\ dx}   
           =    α   3 2     π       ℏ  2    ∫  − ∞   ∞    e  − α  x  2       d x  ∫  − ∞   ∞    e    − α  x  2    2      α  x  2    e    − 2 α  x  2    2      d x   {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {\alpha ^{\frac {3}{2}}}{\sqrt {\pi }}}\ \hbar ^{2}\int _{-\infty }^{\infty }e^{-\alpha x^{2}}\ dx\int _{-\infty }^{\infty }e^{\frac {-\alpha x^{2}}{2}}\ \alpha x^{2}e^{\frac {-2\alpha x^{2}}{2}}\ dx}   
      
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| 使用      ∫  − ∞   ∞    e  − α  x  2       d x =    π α      {\displaystyle \int _{-\infty }^{\infty }e^{-\alpha x^{2}}\ dx={\sqrt {\frac {\pi }{\alpha }}}}   |  
 
 
 
 
 
 
 
 
 
 
 
 
 
           =    α   3 2     π       ℏ  2     (      π α    + α  ∫  − ∞   ∞    x  2    e  − α  x  2       d x   )     {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {\alpha ^{\frac {3}{2}}}{\sqrt {\pi }}}\ \hbar ^{2}{\biggl (}{\sqrt {\frac {\pi }{\alpha }}}+\alpha \int _{-\infty }^{\infty }x^{2}e^{-\alpha x^{2}}\ dx{\biggl )}}   
  
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| 使用     ∫  x  2    e  − α  x  2       d x =      π    erf  (   α   x )   4  α   3 2         −      x  e  − α  x  2       2 α    + C   {\displaystyle \int x^{2}e^{-\alpha x^{2}}\ dx={\frac {{\sqrt {\pi }}{\text{erf}}({\sqrt {\alpha }}x)}{4\alpha ^{\frac {3}{2}}}}\ -\ {\frac {xe^{-\alpha x^{2}}}{2\alpha }}+C}   |  
 
 
 
 
 
 
 
 
 
 
           =    α   3 2     π       ℏ  2     (      π α    + α   [        π      erf  (   α     x )   4  α   3 2       −      x  e  − α  x  2       2 α       ]    − ∞   ∞     )     {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {\alpha ^{\frac {3}{2}}}{\sqrt {\pi }}}\ \hbar ^{2}{\Biggl (}{\sqrt {\frac {\pi }{\alpha }}}+\alpha {\biggl [}{\frac {{\sqrt {\pi }}\ {\text{erf}}({\sqrt {\alpha }}\ x)}{4\alpha ^{\frac {3}{2}}}}-\ {\frac {xe^{-\alpha x^{2}}}{2\alpha }}{\biggl ]}_{-\infty }^{\infty }{\Biggl )}}  ![{\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {\alpha ^{\frac {3}{2}}}{\sqrt {\pi }}}\ \hbar ^{2}{\Biggl (}{\sqrt {\frac {\pi }{\alpha }}}+\alpha {\biggl [}{\frac {{\sqrt {\pi }}\ {\text{erf}}({\sqrt {\alpha }}\ x)}{4\alpha ^{\frac {3}{2}}}}-\ {\frac {xe^{-\alpha x^{2}}}{2\alpha }}{\biggl ]}_{-\infty }^{\infty }{\Biggl )}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/5bea1950eca25f0f4a96c89dbe270e9ca1073bf7) 
           =    α   3 2     π       ℏ  2     (      π α    + α   [      π   4  α   3 2          erf  (   α   ∞ )  lim  x → ∞   −      x  e  − α  x  2       2 α     <
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| 使用      lim  x → ∞    erf  ( x ) = 1   {\displaystyle \lim _{x\to \infty }{\text{erf}}(x)=1}   以及      lim  x → − ∞    erf  ( x ) = − 1   {\displaystyle \lim _{x\to -\infty }{\text{erf}}(x)=-1}  |  
 
 
 
 
 
 
 
 
 
 
           =    α   3 2     π       ℏ  2     (      π α    + α   [      π   4  α   3 2         ( 1 ) −   ( 0 )   ]     −     [      π   4  α   3 2         ( − 1 ) −   ( 0 )   ]     )     {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {\alpha ^{\frac {3}{2}}}{\sqrt {\pi }}}\ \hbar ^{2}{\Biggl (}{\sqrt {\frac {\pi }{\alpha }}}+\alpha {\Biggl [}{\frac {\sqrt {\pi }}{4\alpha ^{\frac {3}{2}}}}\ (1)-\ (0){\Biggl ]}\ -\ {\Biggl [}{\frac {\sqrt {\pi }}{4\alpha ^{\frac {3}{2}}}}\ (-1)-\ (0){\Biggl ]}{\Biggl )}}  ![{\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {\alpha ^{\frac {3}{2}}}{\sqrt {\pi }}}\ \hbar ^{2}{\Biggl (}{\sqrt {\frac {\pi }{\alpha }}}+\alpha {\Biggl [}{\frac {\sqrt {\pi }}{4\alpha ^{\frac {3}{2}}}}\ (1)-\ (0){\Biggl ]}\ -\ {\Biggl [}{\frac {\sqrt {\pi }}{4\alpha ^{\frac {3}{2}}}}\ (-1)-\ (0){\Biggl ]}{\Biggl )}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/d97ef74620922703644cbaf46dda6cf159b98ea1) 
           =    α   3 2     π       ℏ  2     [      π α    + α   (      2   π     4  α   3 2           )     ]     {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {\alpha ^{\frac {3}{2}}}{\sqrt {\pi }}}\ \hbar ^{2}{\Biggl [}{\sqrt {\frac {\pi }{\alpha }}}+\alpha {\biggl (}{\frac {2{\sqrt {\pi }}}{4\alpha ^{\frac {3}{2}}}}\ {\biggl )}{\Biggl ]}}  ![{\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {\alpha ^{\frac {3}{2}}}{\sqrt {\pi }}}\ \hbar ^{2}{\Biggl [}{\sqrt {\frac {\pi }{\alpha }}}+\alpha {\biggl (}{\frac {2{\sqrt {\pi }}}{4\alpha ^{\frac {3}{2}}}}\ {\biggl )}{\Biggl ]}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/c9f74dcc8fcb2866bac5fbd88c9454e0d78e88e7) 
           =   α  π       ℏ  2     [     π   +   1 2     π     ]     {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {\alpha }{\sqrt {\pi }}}\ \hbar ^{2}{\Biggl [}{\sqrt {\pi }}+{\frac {1}{2}}{\sqrt {\pi }}{\Biggl ]}}  ![{\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad ={\frac {\alpha }{\sqrt {\pi }}}\ \hbar ^{2}{\Biggl [}{\sqrt {\pi }}+{\frac {1}{2}}{\sqrt {\pi }}{\Biggl ]}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/bddbe327a1a3da86c9bbfa4ffa542d64e97a5f84) 
          ⟨  p  x   2   ⟩ =   1 2   α  ℏ  2     {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \langle p_{x}^{2}\rangle ={\frac {1}{2}}\alpha \hbar ^{2}}   
动量的误差
            δ  p  x   =   ⟨  p  x   2   ⟩ − ⟨  p  x    ⟩  2       {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad \quad \delta p_{x}={\sqrt {\langle p_{x}^{2}\rangle -\langle p_{x}\rangle ^{2}}}}   
                =      a  ℏ  2    2   −  0  2       {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad \ \ ={\sqrt {{\frac {a\hbar ^{2}}{2}}-0^{2}}}}   
            δ  p  x   =     a  2   2      ℏ   {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad \quad \delta p_{x}={\sqrt {\frac {a^{2}}{2}}}\ \hbar }   
位置误差和动量误差的乘积为
             δ  x   ⋅ δ  p  x   =   1  2 α    ⋅    α 2      ℏ   {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad \quad \delta _{x}\cdot \delta p_{x}={\frac {1}{\sqrt {2\alpha }}}\cdot {\sqrt {\frac {\alpha }{2}}}\ \hbar }   
               =   1 2     ℏ   {\displaystyle \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad \ ={\frac {1}{2}}\ \hbar }   
                                 
这等于       ℏ 2     {\displaystyle {\frac {\hbar }{2}}}   ,因此,处于基态的量子谐振子与海森堡测不准原理一致。
,因此,处于基态的量子谐振子与海森堡测不准原理一致。