A quantum communication method, comprising: modulating a first symbol to an i th direction vector of a first electric wave based on a preset mapping relationship, to obtain a second electric wave, wherein the first symbol is a symbol corresponding to first data, the first electric wave supports M direction vectors, the i th direction vector of the first electric wave is one of the M direction vectors of the first electric wave, the i th direction vector of the first electric wave corresponds to an i th distribution result, the i th distribution result is obtained by converting the second electric wave into an energy quantum, M is a positive integer, and i is an integer; and transmitting the second electric wave, the method further comprising: receiving the second electric wave; converting the second electric wave into N energy quantum sets, wherein one energy quantum set is an empty set or comprises at least one energy quantum, and N is a positive integer; determining a first distribution result of the N energy quantum sets, and determining, based on the first distribution result, that the second electric wave corresponds to an i th direction vector of the first electric wave, wherein the i th direction vector is one of the M direction vectors of the first electric wave, and i is an integer; and determining the first symbol based on the i th direction vector of the first electric wave and the preset mapping relationship. modulating a first symbol to an i th direction vector of a first electric wave based on a preset mapping relationship, to obtain a second electric wave, wherein the first symbol is a symbol corresponding to first data, the first electric wave supports M direction vectors, the i th direction vector of the first electric wave is one of the M direction vectors of the first electric wave, the i th direction vector of the first electric wave corresponds to an i th distribution result, the i th distribution result is obtained by converting the second electric wave into an energy quantum, M is a positive integer, and i is an integer; and transmitting the second electric wave, the method further comprising: receiving the second electric wave; converting the second electric wave into N energy quantum sets, wherein one energy quantum set is an empty set or comprises at least one energy quantum, and N is a positive integer; determining a first distribution result of the N energy quantum sets, and determining, based on the first distribution result, that the second electric wave corresponds to an i th direction vector of the first electric wave, wherein the i th direction vector is one of the M direction vectors of the first electric wave, and i is an integer; and determining the first symbol based on the i th direction vector of the first electric wave and the preset mapping relationship. receiving the second electric wave; converting the second electric wave into N energy quantum sets, wherein one energy quantum set is an empty set or comprises at least one energy quantum, and N is a positive integer; determining a first distribution result of the N energy quantum sets, and determining, based on the first distribution result, that the second electric wave corresponds to an i th direction vector of the first electric wave, wherein the i th direction vector is one of the M direction vectors of the first electric wave, and i is an integer; and determining the first symbol based on the i th direction vector of the first electric wave and the preset mapping relationship.